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MENTAL  FATIGUE 


Works  in  German 

BY 

MAX  OFFNER 

Professor  in  K.  Ludwig's  Gymnasium, 
Munchen 

Author  of  '^Die  Geistige  Ermiidung" 


Die  Psychologie  Charles  Bonnets.  A 
study  in  the  history  of  psychology.  Leip- 
zig, J.  A.  Abel,  1893. 

Willensfreiheit,  Zurechnung  and  Verant- 
wortung.  Discussion  of  important  concepts 
common  to  psychology,  ethics,  and  criminal 
law.     Leipzig,  J.  A.  Abel,  1904. 

Das  Gedachtnis.  The  results  of  experi- 
mental psychology,  and  their  application  to 
problems  of  instruction  and  education. 
Berlin,  Reuther  &  Reichard,  (New  Edition) . 

**The  'Value  of  Forgetting'  is  the  subject 
which  brings  to  a  conclusion  a  book  which 
should  prove  most  useful.  The  usefulness, 
moreover,  will  be  greatly  increased  by  the 
bibliography  and  index  which  are  ap- 
pended."    From  Mind,  January,  1910. 


Eittralt0nal  fagrtjclng^  iMottngrapljB 


MENTAL  FATIGUE 

A  Comprehensive    Exposition  of  the  Nature  of    Mental 

Fatigue,  of  the   Methods  of    Its    Measurement    and 

of  Their  Results,  with  Special  Reference  to 

the  Problems  of  Instruction 

BY 

DR.  MAX  OFFNER 

Professor  at  the  Kgl.  Ludwigs- Gymnasium  at  Munich 

Author  of  "Die  Psychologie  Charles  Bonnets,'"  "Willensfreiheit,  Zurechnung 

und  Veraniworiung'''  and  "Das  Gedachtnis'' 

Translated  from  the  German 

BY 

GUY    MONTROSE    WHIPPLE 

Assistant  Professor  of  Educational  Psychology 

Cornell  University 

Author  of  "A  Manual  of  Menial  and  Physical  Tests.'"  "A  Guide  io  High-school 

Observation,''''  "Questions  in  Psychology y  "Questions  in  School  Hygiene,''''  etc. 


BALTIMORE 

WARWICK  &  YORK,  Inc. 

1911 


Copyright  by 

WARWICK  &  YORK,  Inc. 

1911 


(11 2_ 


AUTHOR'S  PREFACE 

I  am  glad  to  avail  myself  of  the  opportmiity  pre- 
sented by  this  translation  of  my  monograph  on  men- 
tal fatigue  to  make  a  few  alterations  and  extensions 
of  the  original  text  and  to  preface  it  with  a  few  words 
of  introduction. 

From  the  circmnstance  that  the  monograph  has  met 
with  a  favorable  reception  ontside  of  Germany,  I  in- 
fer with  satisfaction  that,  both  in  snbject-matter  and 
form  of  presentation,  it  is  meeting  adequately  the 
needs  of  teachers  and  students  whom  I  wish  to  sup- 
ply with  a  critical,  reliable,  and  intelligible  guide 
through  the  extensive  field  of  investigation  of  fatigue. 

Of  the  great  mass  of  material  that  is  available — 
material  that  is  difScult  to  gather  up  into  a  system- 
atic and  consistent  treatment — I  have  mentioned, 
without  intending  to  disparage  the  works  that  I  have 
omitted,  only  those  contributions  that,  in  my  opinion, 
are  best  fitted  to  introduce  us  to  the  more  intricate 
study  of  fatigue  investigation  and  its  history.  Nat- 
urally, I  have  given  preference  to  G-erman  investi- 
gators, because  it  was  the  German  teacher  primarily 
that  I  sought  to  acquaint  with  the  literature  most 
accessible  to  him.  The  American  teacher  will  be  able, 
without  much  trouble,  to  choose  satisfactory  supple- 
mentary reading  out  of  the  numerous  journals  in  his 


VI  MENTAL   FATIGUE 

own  language  devoted  to  psychology,  pedagogy,  and 
school  hygiene. 

The  terminology  that  I  have  employed  will  prob- 
ably occasion  no  serious  difficulties.  If  it  does,  fur- 
ther information  about  it  and  a  more  detailed  justifi- 
cation of  it  may  be  found  in  my  book  on  memory. 

It  will  afford  me  particular  gratification  if  my  little 
book  shall  avail  to  contribute  in  some  measure  toward 
the  furthering  of  that  intellectual  interchange  that 
has  for  so  long  prevailed,  to  the  mutual  advantage 
of  both,  between  America  and  Germany. 

Dr.  M.  Offnee. 

Munich,  Germany. 


TRANSLATOR'S   PREFACE 

This  translation  of  Offner's  Mental  Fatigue  has 
been  undertaken  because  the  monograph  collates,  sys- 
tematizes, and  appraises  a  mass  of  scattered  and  to 
most  readers  inaccessible  material  that  bears  upon  a 
schoolroom  problem  of  unquestioned  importance. 

The  author,  in  his  introductory  words,  points  out 
that  the  references  are  primarily  adapted  for  Ger- 
man readers.  To  increase  the  usefulness  of  the  book 
for  American  readers,  I  have,  accordingly,  at  his  sug- 
gestion, added  to  the  bibliography  a  partial  list  of  the 
books  and  articles  available  in  English  (Appendix 
I),  and  I  have,  in  several  places  in  the  course  of  the 
text,  inserted  footnotes  that  are  especially  intended 
to  assist  those  who  desire  it  to  gain  further  informa- 
tion concerning  the  several  methods  of  testing  fa- 
tigue, or  to  undertake  for  themselves  experimental 
investigation  in  the  schoolroom  or  the  laboratory. 
For  it  is  one  of  the  merits  of  this  book  that  its  author 
makes  no  pretense  at  finality,  but,  on  the  contrary, 
is  concerned  to  make  evident  the  many  gaps  in  our 
knowledge.  And  one  of  the  objects  of  the  translation 
is,  accordingly,  to  stimulate  others  to  contribute  to 
this  scientifically  interesting  and  practically  impor- 
tant aspect  of  experimental  pedagogy. 

No  attempt  has  been  made  to  render  into  English 

vii 


Vlll  MENTAL    FATIGUE 

the  terms  descriptive  of  the  German  school  system, 
but  the  reader  will  find  in  Appendix  11  an  explanation 
of  the  German  terms  that  have  been  retained. 

In  the  preparation  of  this  translation,  I  am  spe- 
cially indebted  for  assistance  freely  accorded  by  my 
colleagues,  Prof.  E.  B.  Titchener  and  Dr.  L.  R. 
Geissler. 

Guy  Montkose  Whipple. 

Cornell  University,  March,  1911. 


TABLE  OF  CONTENTS. 

Introductory 5 

The  Nature  and  Forms  of  Fatigue 7 

The  Symptoms  of  Fatigue 8 

Symptoms  of  Fatigue  by  Bodily  Work 8 

Symptoms  of  Fatigue  by  Mental  Work 13 

The  Measurement  of  Fatigue 18 

Um-eliability  for  the  Measurement  of  Fatigue  of  the  Sub- 
jective Symptoms 18 

The  Objective  Procedure  and  the  Two  Chief  Groups  of 

Measurement  Methods 20 

The  Physiological  Methods 23 

The  Dynamometer 23 

The  Ergograph 24 

Measurement  of  Fatigue  by  the  Respiration  and  by  the 

Pulse 28 

Beating  Time 28 

Measurement  of  Fatigue  by  Means  of  the  Range  of  Accom- 
modation of  the  Eye .  30 

The  Psychological  Methods 31 

Methods  of  Test- Work 31 

Esthesiometry 31 

Measurement  of   Fatigue   by   Means    of   Other   Liminal 

Values 38 

The  Kinematometer  Method 39 

Method  of  Time  Estimates ^  .     .  41 

The  Algesiometer  Method 41 

Measm'ement  of  Fatigue  by  the  Measurement  of  the  Dura- 
tion of  Mental  Processes 43 

Methods  of  Test-Problems  in  the  Narrower  Sense   ...  44 
(Dictation,  46;  Computation,  46;  Memory,  48;  Com- 
pletion, 49 ;  Cancellation,  52  ;  Copying,  53 ;  Combined 
Methods,  53.) 

Method  of  Continuous  Work 56 

Results 62 

Various  Factors  in  Addition  to  Fatigue  That  Determine 

Efficiency 62 

Practice 62 

Habituation 64 

Swing  or  Fitness  for  Work 66 

Spurt (iS 

Independent  Fluctuations  of  Psychophysical  Energy    .     .  72 

The  Laws  of  Fatigue 74 

The  Phases  of  Fatigue 74 


2  CONTENTS 

Types  of  Fatigue  or  Types  of  Work 75 

Age 77 

Puberty 78 

Length  of  Lesson-Periods 79 

Number  of  Lessons  per  Day  and  per  Week 83 

Days  of  the  Week 84 

Pauses  in  School  Work 85 

( Short  Pauses,  85  ;  The  Noon  Intermission,  86 ;  Sleep, 
88 ;  Vacations,  91 ;  Disadvantages  of  Pauses,  93. ) 

Change  of  Work  :   Special  and  General  Fatigue    ....  94 

Social   Activities 100 

Gymnastics 101 

Fatigue-c-oefficient  of  the  Studies 10^1 

Afternoon   Instruction 106 

School  Program 108 

Fatigue-coefficient  of  the  Teacher 110 

Fatigue-coefficient  of  the  Methods  of  Teaching  and  Learn- 
ing    110 

Individual  and  Class  Instruction 112 

Fatiguability  of  the  Teacher 113 

COXCLUSIOi^        .     .     .     c 116 

Is  it  Permissible  that  Pupils  Be  Fatigued? 116 

Training  in  Mental  Hygiene 118 

More  Intensive  Physical  Development 119 

Bibliography 122 

Appendix  I.     Additional  References  for  American  Readers    .  128 

Appendix  IL     The  Terminology  of  the  German  School  System  130 

Index  of  Names 132 


MENTAL   FATIGUE 

INTRODUCTORY 

In  no  field  of  work  has  experimental  psychology 
come  into  closer  contact  with  the  practical  problems 
of  instruction  than  in  the  investigation  of  fatigue. 
Complaints  against  the  overburdening  of  school 
children  have  been  current  for  a  long  time.  Because 
the  earlier  discussions  of  the  problem,  which  were 
based  upon  general  observations  without  the  assist- 
ance of  exact  methods,  were  inadequate  to  settle  the 
pros  and  cons  of  the  dispute,  experimental  observa- 
tion has  been  applied  to  its  solution.  The  first  con- 
tribution of  this  sort  appears  to  have  been  a  research 
published  by  the  Eussian  psychiatrist,  J.  Sikorski, 
in  1879.  There  have  followed,  from  year  to  year, 
further  studies,  so  that  in  the  last  30  years  an  exten- 
sive literature  of  mental  fatigue  has  accumulated. 
The  very  extent  of  this  literature,  and  the  difficulty 
of  getting  hold  of  it,  and  the  fact  that  thus  far  the  in- 
vestigations have  not  been  brought  to  a  perfectly 
satisfactory  conclusion,  may  account  for  the  circum- 
stance that  schoolmen  have  not,  as  a  rule,  shown  as 
much  interest  in  them  as  they  warrant,  in  spite  of 
their  rather  modest  results.  Indeed,  it  is  not  unlikely 
that  the  results  would  today  be  in  better  shape,  that 
we  should  have,  by  now,  made  better  progress  in  our 
solution  of  this  complex  problem  if  the  schoolmen 

5 


6  MENTAL   FATIGUE 

themselves,  who  have  at  their  disposal  the  richest 
material  for  observation,  had  participated  more  than 
they  have  done  in  the  solution  of  the  problem.  For 
hardly  a  single  one  of  the  investigations  that  have 
been  undertaken  by  teachers  has  failed  to  make  a 
contribution  of  more  or  less  value.  And  so,  to 
awaken  the  interest,  and  to  bring  about  in  any  degree 
the  co-operation  in  the  study  of  fatigue  of  those  in 
intimate  contact  with  the  activities  of  the  school, 
cannot  fail  to  be  worth  while  not  only  for  the  school, 
but  also  for  science. 


THE   NATURE   AND   FORMS   OF  FATIGUE 

What  do  we'mean,  speaking  generally,  hy  fatigue? 

If  we  make  no  attempt  at  explanation  and  inter- 
pretation, but  coniine  ourselves  simply  to  the  phe- 
nomena concerned,  we  designate  by  fatigue  a  condi- 
tion of  our  organism  that  is  developed  by  long-con- 
tinued work,  and  that,  in  addition  to  other  symptoms, 
is  characterized  in  particular  by  a  reduction  in  ca- 
pacity for,  and  pleasure  in,  work.  It  is  true,  these 
symptoms  may,  for  the  time  being,  be  counteracted, 
even  cancelled,  by  antagonistic  factors,  so  that  the 
fact  that  the  condition  of  the  organism  has  been 
altered  may  be  inferred  only  from  other  circum- 
stances. According  to  the  side  of  our  psychophysi- 
cal organism  whose  efficiency  for  work  has  been  re- 
duced— either  by  mental  or  by  physical  work — we 
speak  of  two  forms  of  fatigue — of  bodily  fatigue  as 
fatigue  for  bodily  work,  and  of  mental  fatigue  as 
fatigue  for  mental  work. 

And  according  to  the  nature  of  the  work  by  which 
we  fatigue  our  organism — either  for  mental  or  for 
physical  work — we  distinguish  between  a  fatigue  hy 
bodily  work  and  a  fatigue  hy  mental  work. 

We  shall  at  first  consider  the  fatigue  of  both  sides 
of  our  nature,  divided  according  to  the  nature  of 
its  cause,  of  the  work  which  induces  it. 

Later  we  shall  limit  our  consideration  to  the 
fatigue  of  the  mental  side  of  our  organism  (in  which 
we  are  most  interested),  regardless  of  what  kind  of 
work  has  caused  this  mental  fatigue. 

7 


THE   SYMPTOMS   OF  FATIGUE 

Symptoms  of  fatigue  induced  hy  bodily  worh.  The 
most  important  symptoms  of  fatigue  by  bodily  work 
are  well  known.  If  we  indulge  in  physical  activity 
continuously  and  for  a  long  time,  if  we  walk  or  prac- 
tice gymnastics  or  attempt  mountain- climbing  or 
perform  other  muscular  work,  after  a  certain  time 
there  becomes  evident  a  considerable  quickening  and 
deepening  of  respiration  and  an  acceleration  of  the 
jmlse  rate  (Mosso,  107,  110;  Verworn,  499*),  save  in 
the  case  of  intense  effort,  where  the  opposite  condi- 
tions are  more  likely  to  appear  (Binet  and  Henri, 
150),  and  at  the  same  time  there  appears  a  rise  in 
temperature  sufficient  to  cause  perspiration — at  first 
in  the  members  exercised,  and  then  over  the  entire 
body,  and  finally  a  reduction  of  the  capacity  for  work. 
We  work  more  slowly,  and  hence  accomplish  less  in 
a  given  unit  of  time  than  at  the  beginning ;  our  gait, 
for  instance,  becomes  slower  and  shorter,  and  also 
less  certain,  as  mountain-climbers,  in  particular,  find 
to  their  cost,  and  the  lessened  physical  capacity 
affects  not  only  the  members  that  are  directly  exer- 
cised— here  the  legs — but  other  members  also,  as  in 
walking  the  arms  lose  something  of  their  muscular 


*The  Arabic  numbers  in  parentheses  here  and  elsewhere  in  the 
text  refer,  unless  otherwise  indicated,  to  pages  in  the  references 
assembled  in  the  bibliography  at  the  end. 

8 


THE   SYMPTOMS   OF   FATIGUE  9 

energy  (Mosso,  119).  At  the  same  time  the  feeling 
of  freshness  with  which  we  started  disappears. 
Gradually  we  come  to  feel  dull  and  nncomfortable 
(the  feeling  of  weariness).  Furthermore,  there  is 
developed  a  disinclination  for  fatiguing,  and  ulti- 
mately for  any  kind  of  work,  and  a  desire  to  end  it ; 
we  long  for  rest.  Every  movement,  every  step, 
exacts  greater  effort,  a  greater  expenditure  of  will- 
power. At  the  same  time  our  mental  processes  be- 
come slower  and  less  varied.  Our  conversation, 
accordingly,  grows  languid,  trivial,  and  tends  toward 
empty  word-play;  in  the  end  we  cease  to  talk  alto- 
gether. We  are  also  less  sensitive  to  the  stimuli  of 
the  outer  world.  Thus  the  beauty  of  the  panorama 
makes  little  impression  upon  the  tourist  who  is 
fatigued  by  the  climb  of  the  momitain ;  not  until  he 
has  recuperated  and  regained  something  of  his 
strength  does  it  afford  him  satisfaction.  In  many  in- 
stances excessive  physical  fatigue  brings  it  about  that 
objects  that  strike  the  senses  make  but  little  impres- 
sion, so  that  the  most  beautiful  scenery  is  quickly  for- 
gotten by  people  whose  memory  is  ordinarily  per- 
fectly good.  Even  serious  mental  disturbances  have 
been  observed  as  a  consequence  of  bodily  exhaustion 
(Cf.  Fere,  446  ff. ;  Mosso,  200).  Physical  work,  then, 
unfits  us  for  mental  work  as  well.  These  and  similar 
phenomena  are  psychic  symptoms  of  physical  fatigue, 
and  show  us  that  bodily  activity  results  in  mental,  as 
well  as  in  bodily  fatigue.  In  the  last  resort,  pain 
sets  in,  especially  in  those  members  whose  activity 
is  enforced,  and  it  may  come  to  pass  ultimately  that 
they  refuse  to  function  further,  despite  every  exer- 
tion of  will. 


10  MENTAL   FATIGUE 

The  physiological  processes  concerned  in  the 
muscle  at  work,  in  so  far  as  they  have  been  deter- 
mined at  present,  are  of  two  sorts.  We  owe  to  J. 
Eanke  of  Munich  (1865)  our  first  information  con- 
cerning them.  In  consequence  of  physical  activity 
there  are  formed  in  the  muscles  certain  substances, 
particularly  lactic  acid  (the  same  substance  found 
in  sour  milk)  and  acid  potassium  phosphate. 

These  substances  or  waste  products  thrown  off 
from  the  muscles  are  poisons,  or  toxins  (Mosso, 
108  ff.,  119  ff. ;  Yerworn,  500).  If  one  injects  into  a 
fresh  muscle  these  products  of  the  metabolism  of  a 
fatigued  muscle,  these  fatigue-substances,  as  they  are 
termed,  then  this  fresh  muscle,  without  having  done 
any  work  itself,  at  once  suffers  loss  of  its  contracti- 
bility  and  capacity  for  work.  This  Eanke  demon- 
strated for  a  single  muscle,  while  Mosso  (119  ff.) 
strikingly  confirmed  the  fact  at  Turin  by  injecting 
into  a  live  dog  the  blood  of  another  dog  whose  ner- 
vous system  had  been  fatigued  to  a  state  of  tetanus 
contraction  by  a  strong  electric  current.  And  the 
same  effect  is  produced — this  is  the  second  test — by 
the  injection  of  dilute  phosphoric  acid  and  acid  po- 
tassium phosphate  (Landois,  612). 

But,  by  flushing  with  dilute  gas-free  solution  of 
sodium  chlorid  (0.7  to  1.0  per  cent.),  these  substances 
are  again  eliminated,  as  experiments  upon  the 
muscles  of  animals  have  likewise  shown.  By  this 
process  the  muscle  for  a  short  time  regains  its  origi- 
nal capacity.  And,  indeed,  energetic  movement,  e.  g.y 
shaking  the  hand  fatigued  by  writing,  massaging 
fatigTied  limbs,  as  the  runner  often  does,  frequently 
suffices  to  render  the  muscle  efficient  for  some  time. 


THE   SYMPTOMS   OF   FATIGUE  11 

The  fatigue-substances — such,  is  the  most  obvious  in- 
terpretation— are,  by  these  means,  eliminated  from 
the  muscle.  In  the  case  of  rest-pauses,  the  elimina- 
tion is  effected  by  the  circulation  of  lymph  and  of 
arterial  blood.  To  be  sure,  this  elimination  of  waste 
products  by  the  general  circulation  entails  at  the 
same  time  a  gradual  poisoning  of  the  whole  body, 
if  the  fatigue  poisons  that  are  thus  distributed  are 
not  absorbed  and  rendered  ineffective  by  other  sub- 
stances or  eliminated  from  the  body  through  the  skin 
and  kidneys.  The  question  as  to  how  this  is  accom- 
plished need  not  concern  us  further.  W.  Weichardt 
(Mun.  Med.  Wochenscl%rift,  1904),*  we  may  note, 
believes  that  he  has  at  last  discovered  that  the  body 
forms  an  antitoxin  against  the  fatigue-toxin,  and  he 
reports  that  he  has  succeeded  in  extracting  this  anti- 
toxin and  in  rendering  a  mouse  temporarily  more 
resistant  to  fatigue  by  its  injection.  What  value 
shall  be  attached  to  this  interesting  observation  will 
be  better  known  when  it  has  been  confirmed.  At 
best,  it  offers  only  a  means  for  partially  overcoming 
fatigue,  not  for  cancelling  it  completely,  because 
the  production  of  fatigue-substances  is  only  one  side 
of  muscular  fatigue — the  positive  side.  There  still 
remains  the  negative  side.  This,  which  is  the  more 
important,  consists  in  the  fact  that  the  fat,  and  finally 
the  muscle  itself,  is  gradually  absorbed  during  ac- 
tivity, for  the  consumption,  the  dissimilation  of  the 
materials  of  which  the  body  is  formed  is,  during  ac- 
tivity, more  intense  than  their  assimilation  (dissimi- 
lation and  assimilation  in  the  terminology  of  Hering ; 

♦See  also  his  recent  C7e6er  Ermiidungstoffe,  Stuttgart,  1910. — 
Translator. 


12  MENTAL   FATIGUE 

decomposition  and  recomposition  in  that  of  Her- 
mann). That  this  using  up  of  material  is  present  in 
addition  to  the  accmnulation  of  fatigue- sub  stance  is 
shown  by  the  circumstance  that,  in  spite  of  repeated 
removals  of  the  fatigue  products,  the  capacity  of  a 
muscle  that  is  subjected  to  repeated  stimulation 
diminishes,  and  finally  reaches  zero. 

Max  Verworn  (500  ff.),  at  Gottingen,  has  given  an 
exact  demonstration  of  this  fact  for  the  central 
nervous  system  by  a  celebrated  experiment.  The 
blood  of  a  li^n.ng  frog  was  replaced  by  an  0.8  per  cent, 
gas-free  salt  solution  {i,  e.,  a  solution  totally  lacking 
in  nutritive  substances)  until  the  latter  circulated 
instead  of  blood  in  the  veins  of  the  animal.  Violent 
convulsions  were  then  produced  by  a  weak  dose  of 
strychnine,  while  at  the  same  time  the  circulation  of 
the  neutral  salt  solution  was  discontinued.  The  pow- 
erful excitation  and  the  activity  involved  in  the 
violent  contractions  caused  a  rapid  production  of 
fatigTie-substances.  On  account  of  the  checking  of 
the  salt  solution,  these  substances  were  not  carried 
away,  and  they  soon  induced  a  condition  of  non-ex- 
citability of  the  nerves  (rigor).  So  soon,  however, 
as  these  substances  were  washed  away  with  the  salt 
solution,  the  excitability  returned,  though,  it  is  true, 
it  finally  disappeared,  despite  continued  flushing  out 
of  the  poisons.  Here,  then,  is  fatigue  without  fatigue- 
substances!  If  now,  however,  the  frog  be  flushed 
with  oxygenated  salt  solution,  he  recuperates,  and 
the  condition  of  excitability  is  once  more  restored. 
Yet,  still,  after  a  time  excitability  again  disap- 
pears, despite  continued  flushing  with  the  oxygenated 
solution.     Only  when  the  frog  has  had  injected  in 


THE   SYMPTOMS   OF   FATIGUE  13 

place  of  this  solution  one  of  defibrinated  ox  blood 
(blood  that  is  freed  of  tbe  solid  constituents  that  are 
precipitated  by  coagulation,  and  that  contains,  in 
addition  to  oxygen,  particularly  carbon  and  sodium) 
does  it  maintain  its  excitability  during  many  hours 
of  strenuous  activity. 

Oxygen,  carbon  and  sodium  are,  then,  the  sub- 
stances that  are  especially  required  by  living  tissue 
for  its  activity.  The  consumption  of  these  materials 
is  the  negative  side  of  fatigue.  Verworn  prefers  the 
term  'exhaustion'  for  this  negative  side,  and  un- 
derstands by  'fatigue'  merely  the  positive  produc- 
tion of  fatigue-substances — a  usage  that  is  followed 
by  W.  Elvers  and  by  E.  Kraepelin  of  Munich  {Psy- 
chologische  Arheiten,  I,  571;  see  also  Hermann,  286). 
In  any  event,  these  two  phases  of  the  fatigue  effect 
should  be  kept  quite  distinct  in  mind.  To  replenish 
these  exhausted  materials  in  muscles  and  nerves  is 
the  first  task  of  nutrition  and  of  rest,  especially  of 
sleep,  when  the  use  of  material  (dissimilation  or  de- 
composition) is  so  greatly  reduced  that  the  supply- 
ing of  material  (assimilation  or  recomposition)  so 
far  preponderates  that  there  may  take  place  an  ac- 
cumulation of  surplus  material — a  storage  of  energy. 
Nutrition  and  rest  accordingly  have,  likewise,  two 
sides — a  positive  (the  supplying  of  recuperative  ma- 
terial) and  a  negative  (the  removal  of  fatigue  mate- 
rials). 

Symptoms  of  fatigue  by  mental  work.  The  course 
of  fatigue  by  mental  work  is  an  analogous  one.  Effi- 
ciency gradually  diminishes;  at  first  qualitatively 
(we  make  more  errors),  then  later  on  quantitatively 
(we  accomplish  less  than  we  did  at  first) .    Our  atten- 


14  MENTAL   FATIGUE 

tion  exhibits  marked  fluctuations.  We  become  more 
easily  distracted,  and  find  it  progressively  more  diffi- 
cult to  maintain  a  line  of  thought  and  to  bury  our- 
selves in  a  problem.  Children  are  then  likely  to  be- 
gin to  play  during  school  work.  The  child,  in  such  a 
case,  may  be  said  unconsciously  to  protect  himself 
from  fatigue  by  inattention,  and,  following  Kraepe- 
lin,  we  may  call  his  inattention  a  ^safety  valve.' 
The  observant  teacher,  who  knows  his  pupils,  pos- 
sesses in  this  effect  of  fatigue  a  valuable  sign  of 
warning.  Our  range  of  attention,  at  the  best,  is  cir- 
cumscribed, so  that  things  come  more  and  more  to 
escape  our  notice.  Sense-perception  functions  both 
more  slowly  and  with  less  accuracy;  sensitivity  di- 
minishes. Discrimination  for  every  type  of  per- 
ceptive content  (acoustic,  optic,  tactual  impressions, 
weights,  etc.)  is  less  certain  and  more  subject  to  er- 
ror ;  discriminative  sensitivity  is  impaired.  We  learn 
more  slowly  as  the  work  continues,  i.  e,,  we  learn  a 
less  amount  and  with  less  exactness  in  a  given  time, 
as  is  shown  by  the  increase  of  errors  revealed  by  sub- 
sequent testing.  'Dispositions'  (in  the  sense  used 
by  Offner,  84)  are  less  readily  formed.  In  like  man- 
ner, the  reproduction  of  what  has  been  previously 
acquired,  i.  e.,  the  effectiveness  of  the  'disposi- 
tions,' even  of  those  that  have  been  formed  under 
the  most  favorable  conditions,  is  affected  by  con- 
tinued mental  activity.  Eeproduction  takes  place 
more  slowly  and  less  accurately.  Our  fancy  be- 
comes impoverished,  and  our  thoughts  come  'in 
driblets'  (Meumann,  II,  122;  Offner,  122,  142). 

Finally,  the  capacity  of  the  voluntary  muscles  is 
gradually  affected,  even  though  these  are,  during  the 


THE    SYMPTOMS    OF    FATIGUE  15 

mental  activity,  brought  into  play  little  or  not  at  all. 
If,  for  example,  bodily  energy  be  tested  by  lifting  a 
weight  over  and  over  again  to  a  fixed  height,  or  by 
contraction  of  the  hand,  repeated  nntil  the  movement 
is  no  longer  possible,  then  the  time  at  which  the  con- 
tractions cease  tends  to  appear  much  earlier  after 
severe  mental  work  than  when  we  are  mentally  quite 
fresh  (Cf.  below,  pp.  26  ff.).  Movements  executed 
after  severe  mental  fatigue  are  also  somewhat  less 
certain  and  slower,  as  is  especially  noted  in  the  case 
of  accurately  measureable  movements  of  reaction, 
and,  indeed,  not  seldom  in  the  case  of  speaking  and 
writing.  Mosso  (227,  254  f.,  and  elsewhere)  even 
detected  uncertainty  in  gait  after  long  and  arduous 
mental  activity  in  the  laboratory  and  lecture  room. 
Moreover,  the  unconscious,  or,  as  they  are  termed, 
purely  physiological  processes,  are  affected  by 
fatigue  through  mental  work.  During  such  work, 
respiration  becomes  shallower  and  faster,  but  after 
it,  deeper,  as  in  rest ;  finally,  in  the  case  of  excessive 
fatigue,  respiration  is  again  slower  and  shallower 
(Binet  and  Henri,  33if.).  The  pulse  grows  more 
rapid,  and  may  often  increase  until  palpitation  of 
the  heart  appears  (Mosso,  223),  while,  as  is  well 
known,  during  bodily  fatigue,  pulse  and  respiration 
are  accelerated,  and  the  respiration,  in  particular,  be- 
comes deeper.  In  addition,  on  account  of  the  increase 
in  the  blood  supply  of  the  active  organ,  the  brain, 
there  is  a  rise  of  temperature  in  the  head  with  a  con- 
comitant reduction  of  temperature  in  the  extremities, 
especially  in  the  feet.  Indeed,  we  all  know  the 
cold  feet  and  hot  head  that  we  develop  at  our  desk, 
and  the  coUege  student  who  ^sweats  up'  for  ex- 


16  MENTAL   FATIGUE 

aminations  with  a  wet  towel  about  his  head  is  a 
familiar  figure. 

In  consciousness  there  appear  subjective  symp- 
toms, like  those  accompanying  bodily  work— at  first 
a  mood  of  indifference,  then  a  disinclination  to  pur- 
sue the  fatiguing  work,  together  with  the  desire  for 
a  change.  We  are  'tired'  of  this  work.  Then  a 
feeling  of  languor  becomes  evident,  a  feeling  that  we 
can't  get  hold  of  things,  though  we  still  want  to.  We 
feel  weary  for  any  kind  of  work  (feeling  of  weari- 
ness). Finally,  we  feel  exhausted,  and  crave  noth- 
ing but  rest  and  sleep.  Then,  not  infrequently,  head- 
ache follows — analogously  to  the  soreness  of  the 
fatigued  muscle;  then  restlessness  and  excitement, 
heightened  sensitivity  to  impressions  (hyperes- 
thesia), especially  to  noises,  nervousness,  irritabil- 
ity, ill-humor  and  liabihty  to  passionate  outbreaks. 
Children  are  apt  to  behave  badly  and  to  whine.  All 
these  are  very  important  protective  devices ;  they  are 
warning  signals  that  should  admonish  us  to  cease 
work  and  to  seek  nourishment  and  rest. 

The  physiological  processes  that  we  assume  to 
underlie  fatigue  by  mental  work  may  be  considered, 
speaking  generally,  like  those  for  fatigue  produced 
by  bodily  work,  as  a  production  of  fatigue- sub  stances 
and  a  consumption  of  constitutive  materials,  espe- 
cially in  the  central  nervous  system.  From  this  sys- 
tem, however,  the  fatigue-effect  radiates,  seeing 
that,  on  the  one  hand,  fatigue-poisons  from  the  ac- 
tively working  brain  are  gradually  disseminated 
through  the  organism,  while  on  the  other  hand,  the 
substances  in  the  rest  of  the  body  come  more  and 
more  in  demand,  because  no  adequate  replacement  is 


THE    SYMPTOMS    OF    FATIGUE  17 

afforded  by  direct  mitrition.  This  view  is,  I  grant, 
but  an  hypothesis,  yet  one  that  at  present  has  a  con- 
siderable degree  of  probability,  and  against  which 
there  is,  at  least,  no  serions  objection. 

It  is  scarcely  necessary  to  say  that  the  symptoms 
are  not  the  same  in  all  persons.  Age,  sex,  tempera- 
ment, state  of  health,  nutrition,  and,  more  especially, 
diathesis,  play  a  considerable  role.  Neither  is  the 
picture  of  the  s^Tiiptoms  of  fatigue  always  the  same 
in  the  same  person.  Thus,  for  instance,  in  most  dis- 
eases, especially  in  nervous  diseases  and  during  con- 
valescence, the  phenomena  appear  more  quickly, 
more  intensely  and  more  frequently  than  in  a  time 
of  good  health,  and  the  same  thing  is  true  of  periods 
of  mental  depression. 


THE  MEASUREMENT   OF  FATIGUE 

From  what  has  preceded,  it  is  seen  that  we  have 
at  our  disposal  two  methods  of  undertaking  the 
measurement  of  fatigue — of  that  reduction  in  ca- 
pacity for  work  that  ensues  upon  activity  when  in- 
hibitory substances  are  generated,  and  when  the 
consumption  of  the  constitutent  substances  of  the 
cells  exceeds  its  immediate  replacement  by  the  pro- 
cesses of  nutrition.  First,  the  subjective  method, 
that  finds  a  standard  of  measurement  in  the  sub- 
jective symptoms  of  fatigue,  i.  e.,  in  those  that  are 
conscious  only  to  the  fatigued  person  himself,  and 
secondly,  the  objective  method,  that  seeks  a  standard 
of  measurement  in  modifications  in  the  physiological 
functions  and  in  the  physical  as  well  as  the  mental 
efficiency,  i.  e.,  in  modifications  that  are  perceptible 
to  others  as  well  as  to  the  fatigued  person  himself. 

Unreliability  for  the  measurement  of  fatigue  of 
the  subjective  symptoms.  It  is  evident  that  a  sub- 
jective factor  cannot  be  a  reliable  measure,  however 
useful  it  may  be  as  a  signal.  For  our  own  mood, 
which  not  seldom  varies  quite  independently  of  the 
consumption  of  energy,  exercises  an  obvious  in- 
fluence. When  we  are  happy  we  can  perceive  no 
weariness.  When  we  are  sad  and  depressed,  a  task 
to  be  done  will  all  too  soon  engender  that  feeling 

18 


THE   MEASUKEMENT   OF   FATIGUE  19 

that  we  are  accustomed  to  interpret  as  weariness. 
If  fear  and  anxiety  attack  us,  we  often  forget  all 
weariness,  however  much  exhausted  we  had  felt  be- 
fore. 

A  swallow  of  wine,  a  cup  of  strong  tea  or  coffee, 
a  few  Kola  pastilles  banish  the  feeling  of  languor  and 
give  us  for  a  time  the  illusory  feeling  of  renewed 
freshness  and  undiminished  capacity,  even  after  the 
hardest  kind  of  work. 

And  a  glass  of  beer,  on  the  other  hand,  may,  be- 
fore we  have  done  any  work,  induce  a  feeling  of  lan- 
guor and  render  us  as  unfit  for  work  as  if  we  had  been 
through  the  most  tiresome  toil. 

A  short  time  after  the  chief  meal  of  the  day  we  are 
least  fit  for  mental  work,  but  most  fit  for  bodily  work, 
though  we  do  not  feel  particularly  disposed  to  un- 
dertake it. 

There  are,  too,  many  individuals  who  feel  weary, 
dull  and  ill-disposed  at  the  outset  of  work,  but  who 
gradually  become  fresher,  more  efficient  and  cheerful 
as  their  work  progresses.  Yet  there  can  be  no  such 
thing  as  actual  fatigue  when  the  task  is  just  begin- 
ning. And  there  are  yet  other  individuals  who,  un- 
der protracted  work  when  the  consumption  of  energy 
must  have  long  exceeded  the  supply  of  fresh  energy 
available  at  the  time,  experience  no  feeling  of  weari- 
ness, and  keep  at  work  until  they  suddenly  give  up, 
exhausted.  In  the  former  instance,  therefore,  there 
is  the  feeling  of  weariness  without  fatigue;  in  the 
latter,  actual  fatignie  without  the  feeling  of  weari- 
ness. Hence  the  relation  between  the  feeling  and  the 
psychophysical  condition  is  anything  but  simple,  and 
the  unravelin.^  of  the  threads  that  are  here  inter- 


20  MENTAL   FATIGUE 

woven,  and  tlie  discovery  of  unity  and  regularity  in 
this  correlation,  constitutes  a  special  problem,  wliose 
solution  depends  upon  the  general  view  that  we  hold 
as  to  the  nature  of  feeling. 

The  correspondence,  then,  between  the  subjective 
symptoms,  the  feelings,  and  the  psychophysical  con- 
dition is  far  too  inexact  and  too  ambiguous  to  afford 
us  a  basis  for  the  measurement  of  fatigue.  And  for 
this  reason  no  progress  can  be  made  in  the  under- 
standing of  the  fatigue  question  so  long  as  inquiry 
is  mainly  confined  to  this  well-meaning  but  unre- 
liable witness,  the  weariness  feeling — a  witness,  what 
is  more,  that  is  inaccesible  to  experimental  examina- 
tion and  impossible  of  exact  measurement.  Under 
these  conditions,  too,  the  discussions  concerning  the 
overburdening  of  school  children  can  never  rise  above 
the  level  of  conjecture  and  guesswork,  and  are  wholly 
lacking  in  power  to  convince. 

The  objective  procedure  and  the  two  chief  groups 
of  measurement  methods.  We  must,  therefore,  look 
about  for  better  measures,  for  symptoms  that  avoid 
this  uncertain  judgment  of  the  fatigued  person  him- 
self, for  objective  symptoms  that  are  susceptible  both 
of  systematic  experimentation  and  of  mathematical 
treatment.  These  are,  primarily,  the  physiological 
symptoms  of  fatigue  that  we  have  already  cited.  But 
certain  psychical  symptoms  also  turn  out  to  be  sus- 
ceptible of  determination  and  of  measurement  by 
objective,  i.  e.,  by  external,  observation. 

Accordingly,  the  objective  method  subdivides  into 
two  groups  of  measurement  methods — the  physio- 
logical and  the  psychological.     The  physiological 


THE   MEASUKEMENT   OF   FATIGUE  21 

group  measures  the  decrease  of  mental  efficiency — 
to  the  consideration  of  which  we  shall  henceforth 
limit  ourselves — ^by  means  of  alterations  of  physical 
efficiency  that  it  proceeds  to  test;  in  short,  by  tests 
of  physical  capacity,  and  by  means  of  observing 
modifications  that  appear  in  specific  physiological 
functions.  The  psychological  group,  on  the  contrary, 
confines  itself  to  the  psychical  side,  and  observes  and 
measures  the  decrease  of  mental  efficiency  that  re- 
sults from  mental  activity,  either  in  terms  of  the 
changes  that  appear  in  the  mental  work  itself  that  is 
being  continuously  pursued,  or  by  means  of  tests  of 
mental  efficiency  that  are  introduced  at  definite 
stages  of  the  fatigue-producing  work. 

When  there  are  a  large  number  of  subjects,  par- 
ticularly in  schoolroom  tests,  there  are  two  forms 
of  procedure  that  are  commonly  followed.  Either 
tests  are  given  to  the  class  as  a  whole — ^in  which  case 
there  are  needed  several  tasks  of  equal  length  and 
difficulty,  a  requirement  that  is  hard  to  fulfil — or  the 
class  is  divided  on  the  basis  of  efficiency — putting 
those  of  like  attainment  into  the  same  group — into 
as  many  groups  as  are  wanted  for  tests,  and  one 
group  is  tested  at  a  time,  e.  g.,  as  in  the  experiments 
of  Winch  and  of  Thorndike.  This  admits  the  possibil- 
ity, under  certain  experimental  conditions,  of  apply- 
ing the  same  test-work  at  different  stages  of  fatigue 
—a  possibility  of  distinct  advantage  in  extracting 
conclusions  from  the  experiment.  But,  since  this  pro- 
cedure reduces  the  number  of  subjects,  and  since, 
moreover,  the  same  subject  is  tested  less  often — 
under  some  circumstances  but  once  in  a  day — there 
is  too  much  play  given  to  the  individual  factor.    And, 


22  MENTAL   FATIGUE 

at  the  same  time,  the  chance  of  discovering  this 
factor,  of  making  allowance  for  it  in  the  determina- 
tion of  averages  or  of  basing  conclusions  on  these 
averages  is  diminished  or  entirely  lost.  This  is  a 
disadvantage  of  this  form  of  procedure  which,  to 
me,  seems  to  more  than  outweigh  the  advantage  that 
accrues  from  the  absolute  standard  of  measurement 
that  it  affords,  unless  the  number  of  subjects  or  the 
number  of  experiments  be  sufficiently  large  to  permit 
a  change  of  the  order  of  the  groups,  and  unless  the 
preliminary  tests  of  mental  peculiarities  on  which 
the  distribution  into  groups  is  based  be  very  precise. 

The  test  methods  rest  at  bottom  upon  two,  or  more 
often,  upon  three  assumptions,  the  justification  for 
which  is,  in  the  single  case,  usually  probable,  though 
not  capable  of  absolute  proof.  The  first  assumption 
is  that  the  work  done  really  represents,  both  in  quan- 
tity and  in  quality,  the  work  that  can  be  done  under 
the  conditions  that  prevail — that  the  work,  in  other 
words,  is  a  real  test  of  capacity. 

The  second  assumption — one  that  is  commonly, 
though  not  always  made,  and  whose  problematic  na- 
ture is  usually  well  recognized — is  that  the  test  of 
efficiency  for  the  given  type  of  work  informs  one  also 
of  the  efficiency  for  other,  particularly  for  related, 
types  of  work. 

The  third  assumption  is  that  the  decrease  of  effi- 
ciency during  the  course  of  the  work  is  essentially  a 
fatigue  phenomenon — an  assumption  that  is  indeed, 
in  most  cases,  both  very  obvious  and  very  probable. 


THE  PHYSIOLOGICAL  METHODS 

The  dynamometer.  The  decrease  of  muscular 
force,  more  exactly,  of  ''the  work  that  can  be  done 
by  the  muscle  under  voluntary  contraction"  (Eulen- 
berg,  601),  is  a  purely  physiological  symptom  not 
only  of  bodily,  but  also  of  mental  fatigue,  as  we  have 
already  shown.  J.  Loeb  (1886)  seems  to  have  been 
the  first  to  investigate  ''muscular  activity  as  a  meas- 
ure of  mental  activity."  Soon  afterwards  (1890) 
A.  Mosso  published  his  studies,  "TJeher  die  Gesetze 
der  Ermudung  ["On  the  Laws  of  Fatigue"],  and 
his  well-known  book,  ''La  Fatica''  (1891),  translated 
into  German  in  1892  [and  into  English,  "FatigTie," 
1904] .  Up  to  that  time  the  Collin  dynamometer  had 
been  used  for  measuring  muscular  strength.  This 
instrument  consists  of  a  steel  oval,  which,  when 
gripped  with  the  hand,  indicates  by  a  pointer  the 
pressure  in  kilograms  exerted  by  the  hand.  Ul- 
mann's  dynamometer  is  another  form  that  can  be 
used  either  for  measuring  pressure  or  traction. 

These  measurements  that  are  secured  by  the  use 
of  dynamometers  possess,  however,  little  accuracy, 
in  especial  because  the  subjects  are  by  no  means  apt 
to  exert  in  an  equal  degree  all  the  muscles  concerned, 
so  that  when  fatigue  arises  they  may  easily  shift  the 
groups  of  muscles  and  introduce  into  the  later  meas- 
urements groups  of  muscles  that  had  relatively  little 

23 


24  MENTAL   FATIGUE 

share  in  the  initial  measurements.  These  and  other 
objections  have  been  emphasized  by  Hirschlafl^  (192) : 
Gineff  (39)  and  Claparede  (200  ff.)  have,  however, 
expressed  a  more  favorable  opinion  of  the  dynamo- 
metric  method,  while  Claviere  {Annee  psychologique, 
"\T;I,  1901)  and  Schuyten  have  employed  it  for  meas- 
uring fatigue.* 

The  ergograph.  Having  these  difficulties  in  mind, 
Mosso  constructed,  on  the  plan  of  Helmholtz's  myo- 
graph, a  new  instrument,  known  as  the  ergograph, 
and  this  piece  has  since  been  markedly  improved  by 
later  investigators,  e.  g.,  by  Kemsies,  Vaschide, 
Kraepelin,  and  others. 

In  the  ergograph,  the  forearm  and  hand,  together 
with  the  fingers,  are  firmly  fixed  in  such  a  manner 
that  the  hand  is  extended,  palm  uppermost,  and  with 
only  a  single  finger,  usually  the  middle  finger,  left 
free.  The  flexion  of  this  finger  lifts  a  weight  that 
is  suspended  by  a  cord,  and  the  several  lifts  are  in- 
scribed accurately  upon  a  rotating  drum,  producing 
a  record  termed  an  ergogram.  The  number  of  lifts 
that  the  subject  can  compass  in  a  given  period,  and 
also  the  sum-total  of  the  heights  of  the  several  lifts — 
for  the  automatic  registration  of  which  provision  is 
made  upon  the  best  forms  of  the  instrument — are 
taken  as  the  measure  of  fatigue.  The  Belgian  in- 
vestigator. Mile.  Joteyko,  has  contributed  particu- 
larly to  the  mathematical  treatment  and  interpreta- 
tion of  the  constituent  factors  of  the  ergographic 

*The  reader  will  find  a  fuller  discussion  of  the  dynamometric 
method  and  its  results  in  the  translator's  Manual  of  Mental  and 
PJiysical  Tests,  Warwick  &  York,  Baltimore,  1910.  Methods  of  con- 
ducting most  of  the  tests  of  fatigue  hereinafter  mentioned  may  be 
found  in  the  same  volume. 


THE   PHYSIOLOGICAL    METHODS  25 

curve  (see  her  Lois  de  Vergographie).  Philippe 
( Clavier e,  204),  made  use  of  the  ergometer,  a  sort 
of  non-registering  ergograph,  in  the  use  of  which 
the  experimenter  himself  must  count  the  number  of 
lifts. 

It  is,  of  course,  always  presupposed  in  this  type  of 
measurement  that  the  subject  of  the  test  is  firmly 
resolved  to  continue  flexing  his  finger  or  gripping 
the  dynamometer  as  long  as  he  can  possibly  do  so — 
a  presupposition  that  is  not  susceptible  of  objective 
verification. 

Furthermore,  it  is  essential  that  the  fastening  of 
the  arm  and  hand  and  the  nature  of  the  connection 
between  the  finger  and  the  weight  shall  be  absolutely 
constant  in  every  test — a  requirement  that  is  obvious 
enough,  but  more  easily  stated  than  secured  (Gineff, 

47  fe.). 

But,  even  if  the  assumptions  be  actually  realized, 
the  ergographs,  even  the  improved  patterns,  do  not 
atford  the  reliable  results  that  had  been  expected  of 
them.  To  be  sure,  the  fact  that  the  number  of  muscles 
put  into  play  in  the  use  of  the  instrument  is  consid- 
erably greater  than  the  champions  of  the  method 
suppose  does  not  constitute  a  prohibitive  defect,  pro- 
vided only  that  these  muscles  are  always  the  same. 
But  that  is  precisely  the  difficulty.  It  is  true  to  a  cer- 
tain extent  of  all  ergographs — as  A.  Hoch  and  E. 
Kraepelin  {Psychol.  Arbeit  en,  I,  380  if.)  and  E.  Mul- 
ler  {Philos.  Studien,  XVII,  65  fP.,  13  f.)  showed  defin- 
itely for  Mosso's  instrument,  and  as  Hirschlaff  simi- 
larly showed  for  the  dynamometer — that,  as  fatigue 
develops,  the  contractions  radiate,  until  they  finally 
involve  the  musculature  of  the  shoulder  blade,  so  that 


26  MENTAL   FATIGUE 

the  presupposition  of  permanent  isolation  of  a  few 
muscles  or  permanent  restriction  of  the  muscular  ac- 
tivity to  a  single  controllable  group  of  muscles  can- 
not be  attained.*  And,  what  is  more,  the  funda- 
mental presupposition  itself  is  not  well  enough  estab- 
lished. The  decrease  of  bodily  efficiency  is,  indeed,  a 
frequently-observed  symptom  of  fatigue  induced  by 
mental  labor,  yet,  if  we  leave  out  of  consideration 
fatigue  of  an  excessive  degree  with  its  consequences, 
it  is  not  an  absolutely  uniform  symptom,  so  far  at 
least  as  experiment  has,  up  to  now,  been  able  to  de- 
termine. Not  infrequently  persons  are  found  whose 
middle  finger,  to  speak  with  a  little  exaggeration, 
cannot  be  completely  fatigued  at  all  by  such  move- 
ments as  the  ergograph  demands,  and  this  is  equally 
true,  even  after  mental  work  (Gineff,  10  f.,  49  f.). 
And,  even  if  we  disregard  exceptions  of  this  sort, 
and  have  in  mind  only  those  persons — and  they  form 
the  great  majority — who  are  fatigued  in  body  by 
mental  work,  even  so  there  exists  no  clear  and  re- 
hable  correspondence  between  the  reduction  of  bod- 
ily efficiency  as  measured  by  the  ergograph  and  the 
reduction  of  mental  efficiency.  Kraepelin  {Psychol. 
Arheiten,  I,  415,  and  Ueber  die  Messung,  etc.,  217) 
found  that  his  subject  performed  more  work  on  the 
ergograph  from  an  hour  to  an  hour  and  a  half  after 
the  principal  meal — i.  e.,  at  a  time  notoriously  unfav- 
orable for  mental  work — than  he  did  in  the  morn- 
ing, and  that  he  did  best  of  all  about  9  o'clock,  after 
his  supper.    With  children  Schuyten  {On  V6or-en- 


*However,  this  objection  has  been  ahnost,  if  not  quite,  completely 
met  in  the  elaborate  instrument  devised  by  Bergstrom  (American 
Journal  of  Psychology,  XIV,  1903,  510-54/0)  .—Tr(mslatm\ 


THE   PHYSIOLOGICAL   METHODS  27 

Namiddags,  184)  found  by  means  of  the  dynamom- 
eter that  their  mnscular  strength  was  greater  in  the 
afternoon  than  in  the  forenoon.*  Further,  neither 
Kraepelin's  pupil,  T.  L.  Bolton  {Psychol.  Arheiten, 
IV,  200,  219,  232)  nor  Ginetf  (51  ff.)  was  able 
to  establish  any  definite  relation  between  the 
duration  of  mental  work  and  the  values  ob- 
tained from  the  ergograph.  In  fact,  Bolton 
noted  one  person  whose  ergogram  was  not  re- 
duced, but  increased,  by  two  hours  of  mental  work. 
In  the  same  way,  R.  Keller  of  Winterthur  {Zeits.  f. 
Sch.  Hyg.,  X,  404  f.)  found  on  one  occasion  a  50  per 
cent,  increase  of  muscular  efficiency  after  two  hours 
and  a  half  of  forenoon  instruction.  In  accord  with 
these  instances  are  the  observations  of  Oseretzkow- 
sky  {Psychol.  Arheiten,  III,  612),  who  reported  a 
marked  increase  of  muscular  efficiency  after  severe 
work  in  memorizing,  and,  indeed,  similar  observa- 
tions were  in  some  cases  made  by  Mosso  (287). 

Finally,  the  will,  and,  still  more,  the  feelings  and 
moods,  may  either  reduce  or  increase  the  ergographic 
performance — a  well-known  experience  that  has  been 
subjected  to  careful  study  by  Fere  {Travail  et 
plaisir)  and  by  Meumann  (II,  97  ff.). 

Hence  the  method  of  measuring  fatigue  by  the 
ergograph,  even  if  it  should  prove  to  be  adapted  for 
exact  measurement  of  bodily  efficiency,  has  turned 
out  not  to  be  sufficiently  reliable  for  the  measurement 
of  mental  fatigue,  at  least  not  sufficiently  reliable  for 
general  use,  though  perhaps  with  some  persons  and 


*A  contrary  result  has,  however,  been  reported  in  Smedley's 
investigation  made  upon  public-school  children  at  Chicago;  see 
my  Manual  of  Mental  and  Physical  Te^ts,  p.  96. — Translator. 


28  MENTAL.  FATIGUE 

in  some  degree  the  correspondence  that  is  assumed 
may  obtain. 

Measurement  of  fatigue  by  the  respiration  and  by 
the  pulse.  Still  less  feasible  are  other  very  fluctuat- 
ing physiological  symptoms  that  are  affected  by 
many  influences  difficult  of  control,  for  example,  to 
name  the  most  prominent,  the  retardation  and  dimi- 
nution of  the  pulse  and  the  shallowing  of  respiration 
that  frequently  ensue  upon  mental  work.  Binet  and 
Henri  (33  if.)  have  reported  in  some  detail  upon 
these  methods  of  measuring  fatigue.  Under  some 
circumstances,  one  can,  to  be  sure,  infer  the  presence 
of  mental  fatigue  from  the  presence  of  these  phe- 
nomena, but  yet  one  does  not  always  find  them  when 
fatigue  is  present,  and  even  if  they  are  to  be  thought 
of  as  symptoms  of  fatigue,  still  it  is  impossible  to 
argue  from  their  magnitude  to  the  magnitude  of  the 
fatigue,  since  it  is  impossible  to  demonstrate  any 
proportionality  between  the  two. 

Beating  time.  Closely  related  to  the  ergographic 
method  is  the  method  of  beating  time.  This  method, 
which  has  been  recommended  by  W.  Stern  {Diff. 
Psych.,  117  f.,  122  fiP.),  has  been  much  used  by  M. 
Lobsien  and  W.  A.  Lay  (especially  406  ff.)  and  has 
found  particular  favor  in  America  (Grilbert,  Wells) 
in  tests  of  groups  under  the  name,  ^'the  tapping 
test.'^* 

This  method,  like  the  preceding,  tests  efficiency  by 
resort  to  a  physical  ]3rocess,  which,  like  every  bodily 
activity,  is  naturally  influenced  by  mental  factors. 

♦The  tapping  test  of  Gilbert  and  Wells,  however,  is  not  identical 
with  the  test  of  beating  time  here  described,  since  in  tapping  the 
subject  is  instructed  to  tap  continuously  at  his  mawwial  rate.  See 
reference,  footnote,  p.  24. — Translator. 


THE   PHYSIOLOGICAL   METHODS  29 

The  subjects  are  asked  to  beat  time  upon  a  tele- 
graph key,  following  some  assigned  rhythm,  e.  g.,  a 
three-beat  measure,  at  whatever  rate  best  suits  them. 
These  movements  are  registered  automatically  upon 
a  rotating  drum  (kymograph).  The  number  and  the 
rate  of  the  movements  are  then  used  to  measure  the 
amount  of  psychophysical  energy.  For  every  person 
has  his  own  rate — a  natural  individual  rate  of  flow 
of  his  psychical  life  (Stern,  115,  and  Meumann,  II, 
117).  The  slower  the  tapping  is  done  in  comparison 
with  this  normal  rate,  the  greater,  so  the  inference 
runs,  is  the  f  atigTie.  Here,  again,  it  is  true  that  men- 
tal fatigue  is  not  seldom  accompanied  by  retardation 
of  other  activities — in  this  instance,  of  the  tapping. 
But  there  is  as  little  uniformity  and  certainty  in  the 
relation  of  this  decrease  of  rate  to  increase  of  fatigue 
as  there  is  between  muscular  efficiency  and  mental 
fatigue,  or  between  the  spatial  limen  and  mental 
fatigue.  Interest  and  will,  mood,  and  so  forth,  play  5x: 
a  part,  and,  in  addition,  the  rhythmic  tapping  itself 
very  often  develops  a  condition  of  excitement  that  )^\ 
for  the  time  being  can  completely  cancel  tlie  effects 
of  fatigue  (Meumann,  II,  101). 

What  is  really  measured  in  this  test  is  only  the 
speed  of  beating  time — an  action  that  is  primarily 
physical  in  character — and,  indirectly,  through  it  the 
physical  energy  of  the  subject.  This  energy  is  natur- 
ally augmented  during  the  period  following  meals. 
Thus  one  critic  of  the  method,  E.  Meumann  (II,  117, 
136),  found  that  the  rate  of  beating  time  was  acceler- 
ated after  the  mid-day  meal,  just  as  Kraepelin  had 
demonstrated  an  increase  in  ergographic  perform- 
ance after  meals. 


30  MENTAL   FATIGUE 

Measurement  of  fatigue  by  means  of  the  range  of 
accommodation  of  the  eye.  A.  Baur,  a  training- 
scliool  physician  of  Grmiind,  Swabia,  has  made  use  of 
a  new  method  of  measuring  mental  or  bodily  fatigue 
in  terms  of  muscular  efficiency.  By  means  of  Schein- 
er's  experiment,  he  observed  the  very  sensitive 
muscle  of  accommodation,  and  found  that  the  range 
of  accommodation,  i.  e.,  the  distance  between  the  far- 
point  and  the  near-point,  is  increased  in  conditions  of 
fatigue  and  exhaustion.  Nevertheless,  his  investi- 
gations have  not  yet  been  carried  far  enough  to  per- 
mit the  recognition  of  such  a  definite  parallelism  be- 
tween increase  of  fatigue  and  increase  of  the  range 
of  accommodation  as  must  be  demanded  for  exact 
measurements  of  fatigue.  We  must  await  further 
comparative  investigations  to  gain  insight  on  this 
point.* 

So  far  as  the  other  physiological  methods  are  con- 
cerned, this  insight,  as  we  have  seen,  has  already 
been  attained,  and  it  has  demonstrated  that,  despite 
the  many  valuable  suggestions  that  these  methods 
have  afforded,  they  are  so  unreliable  that,  for  the 
present,  they  can  be  disregarded  in  our  search  for 
exact  measurements  of  mental  fatigue. 

♦Since  this  was  written,  Baur  has  reported  further  results  that 
disclose,  seemingly,  a  very  close  relation  between  the  range  of 
accommodation  and  the  condition  of  the  central  nervous  system. 
See  Intern.  Mag.  of  School  Hygiene,  VII,  January,  1911,  52-92. — 
Translator, 


THE   PSYCHOLOGICAL   METHODS 

Methods  of  test-work.  A  better  case  may  be  made 
out  for  the  psychological  methods.  In  the  first  group 
of  them  the  subject  carries  out  some  form  of  mental 
work  as  a  test  of  his  efficiency  (test-methods).  Some 
of  these  methods  can  be  undertaken  with  very  simple 
and  very  short  tests  of  efficiency. 

Esthesiometry.  In  this  category  belongs  the  de- 
termination of  the  degree  of  fatigue  by  the  measure- 
ment of  cutaneous  sensitivity.  The  discrimination 
of  two  points,  which  forms  the  essential  feature  of 
the  measurement,  is  a  mental,  not  a  physical  pro- 
cess, as  H.  Griesbach  in  his  later  articles  (Inter. 
Archiv.,  1, 1905)  has  attempted,  in  opposition  to  Hel- 
ler {Wien.  Med.  Presse,  1899)  and  others,  to  main- 
tain. And  it  is  a  mental  magnitude — whether  we 
call  it  attention,  as  Griesbach  himself  originally 
thought  {Energetik,  8,  87),  or  whether  we  name  it 
mental  energy,  that  is,  the  possibility  that  physical 
processes  appear  in  consciousness  (Lipps,  60  if.; 
Offner,  44) — that  is  measured  in  this  act  of  discrimi- 
nation. It  is,  of  course,  true,  as  Motchoulsky  espe- 
cially emphasizes,  that  physical  factors  in  the  nerves 
of  the  skin  are  also  operative.  But  so,  also,  are 
physical  factors  operative  in  the  discrimination  of 
colors,  of  pitches,  of  tone  intensities,  in  the  estima- 
tion of  weights,  of  lengths,  etc.    In  what  mental  pro- 

31 


32  MENTAL   FATIGUE 

cess  are  they  not,  as  a  matter  of  fact,  concerned! 
But  no  one  would  think  of  calling  such  psychophysi- 
cal investigations  physiological,  even  though  they 
were  first  attacked  by  physiologists. 

So,  too,  in  this  case,  it  was  a  physiologist,  E.  H. 
Weber  of  Gottingen,  who  discovered  long  ago  (1834) 
that  the  shortest  distance  at  which  the  contact  of  two 
points  is  still  felt  as  separate,  i.  e.,  as  the  contact  of 
two  cutaneous  points,  that  the  spatial  limen,  as  the 
distance  was  named  by  Fechner,*  varies  at  different 
regions  of  the  body,  and  on  different  persons  in  the 
same  region.  The  relative  values  of  the  spatial  limen 
for  different  regions  are,  however,  approximately 
constant  for  all  persons. 

Now,  these  liminal  values  are  increased  by  physical 
work.  Griesbach  {Energetik,  1895)  appears  to  have 
been  the  first  to  observe  that,  in  a  given  individual, 
the  limen  is  also  increased  by  strenuous  mental  work. 
He  found — and  Eulenberg  soon  after  confirmed  the 
observation  on  himself  {Hyg,  Rundschau,  VIII,  600) 
— that  two  closely  approximated  blunt  compass 
points  applied  gently  to  the  skin  at  the  same  moment 
are,  as  a  rule,  after  fatiguing  work,  perceived  as  one 
point,  whereas  they  had  been  still  perceived  as  two 
before  the  work  was  begun.  In  general,  the  increase 
of  f  atignie  goes  hand  in  hand  with  the  increase  of  the 
spatial  limen,  save  that,  under  conditions  of  exces- 
sive fatigue,  combined  with  mental  depression  and 
feelings  of  discomfort,  there  appears,  for  reasons  as 


*0.  Ktilpe  {G-rundriss  d.  Pspch.,  38  f.,  350  ff.  [see  English  trans- 
lation, Outlines  of  Psychology,  pp.  36  f.  and  337  ff.] )  and  others  have 
shown  that  this  determination  does  not  afford  a  liminal  value  in 
the  strict  sense  of  modern  psychophysics. 


THE   PSYCHOLOGICAL    METHODS  33 

yet  unexplained,  a  considerable  diminution  of  the 
spatial  limen.  These  compasses  and  like  instru- 
ments, such  as  Eulenberg,  Ziehen,  Spearman,  Eb- 
binghaus,  Binet,  Abelson  [Jastrow,  Titchener]  and 
others  have  contrived  for  the  same  purpose,  are 
called  esthesiometers,  and,  accordingly,  the  spatial 
limen  or  the  compass-point  method  is  also  termed  the 
esthesiometric  method. 

Griesbach's  subjects  were  pupils  in  the  Gymna- 
sium and  the  Oherrealschule*  (technical  high  school) 
at  Miihlhausen,  as  well  as  teachers  in  training,  and, 
in  his  later  tests,  teachers,  soldiers  and  other  adults 
as  well.  He  secured  his  measurements  from  several 
regions  of  the  body,  e.  g.,  the  forehead,  the  cheek- 
bone, the  tip  of  the  nose,  the  mucous  membrane  of 
the  lower  lip,  the  ball  of  the  right  thumb  and  the  tip 
of  the  right  forefinger.  As  he  found  that,  in  general, 
the  sensitivity  of  these  regions  varied  in  like  manner, 
he  finally  confined  himself  to  the  testing  of  a  few  re- 
gions— at  times,  indeed,  to  a  single  region,  particu- 
larly to  the  cheek-bone,  as  being  the  most  sensitive 
place.t 

Nevertheless,  this  correspondence  of  the  different 
regions  held  true  only  in  a  general  way,  as  is  shown 
especially  by  the  comparison  of  measurements  taken 
on  symmetrical  zones  of  the  two  halves  of  the  body, 
and  these,  too,  are  neither  structurally  nor  func- 
tionally absolutely  alike.     After  more  abstract  ac- 

*0n  the  technical  terms  descriptive  of  the  German  school  sys- 
tem, consult  Appendix  II. — Translator. 

fSchuyten  of  Antwerp  prefers  to  test  that  part  of  the  cheek  that 
lies  vertically  under  the  outer  angle  of  the  eye  at  the  level  of  the 
tip  of  the  nose,  and,  with  good  reason,  recommends  that  measure- 
ments be  taken  on  both  sides  of  the  face. 


34  MENTAL    FATIGUE 

tivities,  e,  g.,  after  grammatical  exercises,  memoriz- 
ing, arithmetic,  and  a  great  part  of  mathematics,  as, 
in  general,  after  mental  activity,  it  may  be  observed 
that,  with  right-handed  persons,  the  measurements 
of  the  right  side  of  the  body — which,  as  is  well  known, 
has  its  centers  in  the  left  half  of  the  brain  (that 
hemisphere  that  is  used  in  mental  work,  especially 
when  thinking  in,  and  by  means  of,  words) — have 
yielded  higher  liminal  values,  even  though  the  values 
were  identical  for  the  two  sides  before  the  activity. 
After  activity  that  is  predominatingly  physical,  on 
the  contrary,  the  liminal  values  are  apt  to  be  higher 
on  the  left  side.  Finally,  in  the  case  of  bodily  activity 
under  concentrated  attention,  these  liminal  values 
often  differ  but  little  from  one  another.  With  left- 
handed  persons  all  this,  as  a  rule,  is  reversed. 

Griesbach's  method  found  many  adherents.  Thus, 
his  procedure  was  followed  by  E.  Keller  upon  pupils 
in  the  Gymnasium  and  industrial  school  at  Winter- 
thur ;  by  Th.  Vannod  upon  pupils  of  a  Bernese  inter- 
mediate school ;  by  L.  Wagner  in  the  Gymnasium  at 
Darmstadt;  by  B.  Blazek  in  a  Realgymnasium  at 
Lemberg ;  by  Th.  Heller  upon  feeble-minded  children 
at  Vienna,  and  by  E.  Schlesinger.  These  investiga- 
tions led  to  results  in  the  main  accordant  with  those 
of  Griesbach.  More  recently  Bonoff,  a  school  phy- 
sician at  Sofia,  has  worked  with  this  method  upon 
scholars  of  the  Gymnasium,  and  Prof.  P.  M.  Noikow 
of  Sofia  upon  teachers  and  candidates  for  teaching, 
not  to  mention  others,  like  Ferrari  in  Italy,  Sakaki 
in  Japan,  Ley,  Schuyten  and  Michotte  in  Belgium. 
A.  Binet  and  J.  Joteyko  have  also  used  and  com- 
mended the  method.    (Cf.  also  Griesbach,  Int.  Arch, 


THE   PSYCHOLOGICAL   METHODS  35 

Schulhyg.,  I,  1905,  and  Verh.  d.  IX  Jahresver.,  233.) 
And,  last  of  all,  there  has  appeared  another  success- 
ful champion  of  Griesbach's  method  in  the  person  of 
W.  E.  Abelson,  who  has  carried  out  very  painstaking 
and  extensive  experiments  upon  pupils  at  Rennes 
and  at  London.  The  proof  of  a  certain  degree  of 
correlation  between  the  esthesiometric  records  and 
actual  observation  in  the  schoolroom  has  developed 
confidence  for  the  method,  and  has  attracted  a  good 
deal  of  attention. 

On  the  other  hand,  the  Griesbach  method  has  been 
sharply  criticized  by  the  Kraepelin  school.  In  the 
first  place,  Kraepelin  {Ueher  die  Messung,  etc.),  and 
especially  Th.  Bolton  {Psychol.  Arheiten,  IV),  on  the 
basis  of  extensive  laboratory  tests  that  Bolton  con- 
ducted with  an  improved  esthesiometer — though,  to 
be  sure,  upon  a  single  observer — made  it  evident  that 
the  procedure  advised  and  adopted  by  Griesbach  and 
his  adherents,  when  carried  out  in  the  hasty  way  that 
they  had  followed,  was  quite  inadequate  for  an  exact 
determination  of  the  spatial  limen,  simply  on  ac- 
count of  the  difficulty  of  applying  the  two  points  with 
absolute  simultaneity,  and  with  the  same  pressure  in 
successive  trials ;  that,  on  the  contrary,  an  absolutely 
reliable  determination  of  the  spatial  limen  is  such  an 
elaborate  undertaking  that  the  method  cannot  be 
recommended  for  group  tests.  Secondly,  and  this  is 
a  more  weighty  objection,  Bolton  insists  (196  ff.)  that 
there  exists  no  definite  relation  between  degree  of 
fatigue  and  magnitude  of  the  spatial  limen,  although 
it  is  not  unlikely,  but  ofttimes  quite  evident,  that  men- 
tal fatigue  does  have  some  effect  upon  the  limen.  As 
as  matter  of  fact,  discriminative  sensitivity  is  often 


36  MENTAL   FATIGUE 

increased  by  emotional  excitement,  just  as  it  is  in  the 
condition  of  hyperesthesia  that  follows  excessive 
fatigue.  "The  experimental  errors  and  the  varia- 
tions of  the  spatial  limen  set  up  by  other  causes  are 
so  great  that,  despite  weeks  of  the  most  painstaking 
work  with  a  subject  trained  in  physiological  experi- 
mentation, we  have  not  been  able  to  determine  defi- 
nitely the  effect  of  fatigue  upon  the  limen. ' '  Similar 
negative  conclusions  have  been  reached  by  other  in- 
vestigators, e.  g.,  by  J.  H.  Leuba  {Psych.  Rev.,  VI), 
who  worked  with  adults  of  both  sexes,  and  with  col- 
lege students,  and  who  was  especially  careful  to 
guard  against  disturbing  conditions  (thickness  of  the 
skin,  blood  supply,  skin  temperature,  general  physi- 
cal condition  and  the  like),  and  by  Prof.  C.  Eitter  of 
Ellwangen  [Zeits.,  XXIV),  who  undertook  fatigue 
measurements  upon  Gymnasial  students;  by  J.  B. 
Germann,  who  employed  but  a  single  observer,  and 
also  by  Gineff  (15  ff.)  and  by  Meumann  (II,  91  ff.). 

Nevertheless,  it  cannot  be  denied  that  the  measure- 
ments of  the  decrease  and  increase  of  what  we  term 
the  spatial  limen,  as  secured  with  this  method  by 
Griesbach  and  many  others  after  him,  do  show  a  de- 
gree of  accordance  that  cannot  be  entirely  attributed 
to  bias,  to  autosuggestion  on  the  part  of  the  experi- 
menter, or  to  that  suggestion  of  the  observer  to  which 
Tawney  in  particular  (Philos.  Studien,  XIII)  calls 
attention,  even  if  this  source  of  disturbance  has  been 
present  in  every  instance.  Again,  the  inaccuracy  of 
procedure,  for  which  Griesbach  has  been  criticized, 
could  at  the  most  result  merely  in  concealing,  or  in 
making  less  evident,  the  correspondence  between  the 
degree  of  fatigue  and  the  spatial  limen,  provided  such 


THE   PSYCHOLOGICAL   METHODS  37 

a  correspondence  were  actually  present ;  it  could  not 
have  produced  in  so  many  instances  an  illusory  ap- 
pearance of  a  correspondence  if  no  such  thing  existed 
at  all.  It  must  be  added  that  the  method  of  Bolton  and 
others,  as  Griesbach  shows  in  his  later  investigations 
{Int.  Arch.  f.  Schulhyg.,  I),  is  by  no  means  free  from 
criticism,  and  that  the  results  in  many  instances  are 
susceptible  of  another  interpretation  than  that  given 
them  by  Bolton.  Moreover,  the  coincidence,  to  which 
we  have  referred,  between  the  esthesiometric  meas- 
urements and  conunon  observation,  especially  in  the 
schoolroom,  speaks  for  their  utility  as  a  measure  of 
fatigue,  more  correctly  as  a  method  of  measurement 
for  one  of  the  symptoms  of  fatigue. 

And  so  it  seems  as  if  with  this  method  we  may, 
after  all,  come  very  considerably  nearer  to  mental 
fatigue  than  with  the  ergographic  or  any  other 
method  that  is  based  upon  physiological  symptoms ; 
and  this  will  be  so  much  the  more  the  case  when  we 
have  succeeded  in  attaining  technically  satisfactory 
measurements — e.g., in  especial,  absolute  simultaneity 
of  application  of  the  compass-points,  absolute  equal- 
ity of  pressure  in  all  applications  (the  more  compli- 
cated instruments  already  make  this  possible),  and 
equality  of  temperature  of  the  instrument  and  of  the 
skin — and  when  we  have  also  succeeded  in  avoiding 
suggestion  (which  may  affect  the  experimenter  as 
well  as  the  subject)  and  in  eliminating  what  is  known 
as  the  '^paradoxical  error,"  i.  e.,  the  perception  of 
two  points  when  but  one  is  applied.* 

And  when  comparison  is  made  of  the  values  ob- 
tained in  different  regions  of  the  body  of  the  same 


*See  Gineff  (15ff.). 


38  MENTAL   FATIGUE 

person,  it  must  be  remembered  that  the  richness  of 
the  nerve-endings  in  the  different  organs  varies,  as 
does  also  the  thickness  of  the  skin;  and  again,  that 
one  organ  or  one  region  of  the  body  may  be  more 
practiced  for  this  kind  of  discrimination  than  other 
organs  or  regions. 

Finally,  when  comparison  is  made  of  the  esthesio- 
metric  values  of  the  same  regions  of  the  body  in  dif- 
ferent persons,  it  must  be  remembered  that,  in  this 
case,  too,  the  thickness  of  the  skin,  the  degree  of 
practice  of  the  person  in  general,  as  well  as  of  the 
organ  in  question,  condition  individual  differences, 
and  that,  furthermore,  age,  sex,  ability  to  observe, 
sensory  type,  capacity  for  concentration,  the  general 
level  of  mental  development,  as  well  as  external 
social  relations  (Vannod),  all  may  be  responsible  for 
individual  differences  that  must  be  taken  into  account 
before  greater  or  lesser  degree  of  fatigue,  and  thus 
of  the  fatiguability  of  the  several  individuals,  can  be 
determined  in  comparison  one  with  another.  All 
these  values  have,  however,  so  far  only  an  individual 
or  relative  value. 

Measurements  of  fatigue  hy  means  of  other  liminal 
values.  The  difficulties  that  appear  in  this  determi- 
nation of  the  spatial  limen  in  consequence  of  the 
variation  in  anatomical  conditions  in  the  same  indi- 
vidual do  not  appear  in  the  determination  of  other 
liminal  values. 

Meumann  {II,  92)  and  Grineff  (17)  have,  therefore, 
good  warrant  for  asserting  that  we  might  just  as 
well,  and  even  better,  use  as  an  index  of  fatigue  any 
other  limen,  i.  e.,  that  we  might  measure  fatigue  in 
terms  of  the  magnitude  (which  varies  with  the  degree 


THE   PSYCHOLOGICAI.   METHODS  39 

of  mental  freshness)  of  any  other  stimulus  that  is 
just  perceptible,  and  that  just  arouses  a  sensory  ex- 
perience, or  the  similarly  varying  magnitude  of  the 
difference  between  any  two  stimuli  that  arouses  two 
just  noticeably  different  sensory  experiences,  e.  g,, 
the  limen  for  weak  auditory  or  for  weak  pressure 
stimuli.  This  assertion,  indeed,  seems  to  be  con- 
firmed by  Baur's  experiments  {Das  kranhe  Schul- 
hind,  175,  note),  for  he  found  that  the  distance  at 
which  a  watch  must  be  placed  in  order  that  its  tick- 
ing might  still  just  be  heard  decreased  as  fatigue  in- 
creased ;  similarly,  he  found  symptoms  of  fatigue  in 
the  pupillary  reflex,  in  the  decreasing  size  of  the  field 
of  vision  and  in  certain  variations  in  the  recognition 
of  colors,  although  these  symptoms  have  not  as  yet 
been  subjected  to  systematic  study. 

The  kinematometer  method.  Nor  have  we  as  yet 
any  thorough  examination  of  what  may  be  termed 
the  kinematometer  method.  The  kinematometer,  or 
movement  measurer,  is  an  instrument  constructed 
by  G.  W.  Storring  that  indicates  in  angular  degrees 
the  magnitude  of  the  movement  of  a  member  that  is 
fastened  in  it.  Meumann  (II,  94)  has  worked  with  it, 
but  his  pupil,  D.  Gineff,  gives  (63  ff.)  a  more  detailed 
account  of  the  method.  Gineff  caused  his  subject, 
whose  eyes  were  blindfolded,  to  execute  for  an  hour 
or  two  a  given  form  of  movement,  e.  g.,  a  swing  of 
the  forearm  over  a  horizontal  baseboard,  with  the 
elbow  as  a  fixed  point  of  rotation.  The  extent  of  this 
movement,  which  was  known  as  the  normal  move- 
ment, was  regulated  by  two  fixed  terminal  points  or 
stops.  Then  he  removed  one  of  these  stops,  and 
directed  the  subject  to  make  the  movements  that 


40  MENTAL   FATIGUE 

followed,  the  comparison  movements,  equal  to  the 
first  or  normal  movement,  as  judged  by  the  sensa- 
tions set  up  by  the  movement,  i.  e.,  to  make  the  move- 
ments of  such  an  extent  that  no  difference  could  be 
detected  between  the  ^feeP  set  up  by  it  and  the 
'feeP  set  up  by  the  normal  movement.  The  more 
delicate  the  differential  sensitivity  for  sensations  of 
movement,  the  closer  will  the  comparison  move- 
ments approximate  to  the  normal  movement,  or  the 
smaller  will  be  the  error  of  estimation.  In  a  fatigued 
condition,  larger  errors  are  made,  i.  e.,  the  compari- 
son movements  then  exhibit  greater  deviations  from 
the  normal  movement  than  in  a  fresh  condition,  be- 
cause the  differential  sensitivity  (sensible  discrimi- 
nation) for  sensations  of  movement  suffers  from 
fatigue,  just  as  we  saw  it  to  be  affected  in  the  case 
of  other  sensory  experiences.  In  this  instance,  the 
error  introduced  by  fatigue  is  not  distributed  evenly 
to  either  side  of  the  normal  movement,  but  there  is  a 
strong  tendency  to  make  the  comparison  movement 
shorter  than  the  normal  movement,  or,  in  other 
words,  to  overestimate  the  former.  The  reason  lies 
in  this,  that,  in  fatigue  and  exhaustion,  as  we  all 
know,  every  movement  is  difficult  and  slow  of  execu- 
tion ;  small  movements  are  accompanied  by  a  feeling 
of  tension  or  activity  (feeling  of  exertion  of  will)  as 
intense  as  that  that  accompanies  larger  movements 
made  in  fresh  condition.  This  feeling  of  effort,  how- 
ever, serves  us  as  a  secondary  criterion  of  the  magni- 
tude of  any  movement  that  we  make.  Only  occa- 
sionally do  the  comparison  movements  show  a  tend- 
ency to  be  much  longer,  viz.,  when  the  subject  be- 
comes cognizant  of,  and  therefore  strives  to  counter- 


THE   PSYCHOLOGICAL   METHODS  41 

act,  that  first  natural  tendency  to  make  the  compari- 
son movement  shorter. 

On  the  basis  of  his  experiments  (nnfortimately 
limited  to  a  single  subject),  Ginetf  has  reached  the 
conviction  that  this  kinematometer  method  is  more 
reliable  than  the  ergographic  method.  That  his  ex- 
pectation will  be  confirmed  is  not  improbable ;  in  any 
case,  the  method  is  certainly  simpler,  and  hence  more 
easily  applied  in  individual  school  tests,  than  is  the 
ergographic  method. 

Method  of  time  estimates.  The  estimation  of  time 
has  been  applied  to  the  measurement  of  fatigue  by 
M.  Lobsien  at  Kiel  {Ermildimg  u.  Zeitsclidtzung). 
A  duration  of  one  minute  was  filled  by  rapid  metro- 
nome beats.  The  subjects  (10-year-old  pupils  of  a 
Kiel  common  school)  had  directly  afterward  to  re- 
cord their  estimate  of  the  length  of  this  time.  The 
average  estimation,  as  computed  from  the  total  of 
the  estimates,  increased  with  some  fluctuations  from 
the  beginning  of  the  first  hour,  when  it  averaged  2.43 
minutes,  to  the  last  hour,  when  it  reached  4.03 
minutes.  In  view,  however,  of  the  notorious  unre- 
liability of  children  and  of  many  adults  in  estimating 
time  intervals,  the  estimation  thus  demanded  on  the 
basis  of  a  single  presentation  of  the  object  to  be 
estimated  seems  to  afford  a  very  unreliable  measure 
of  fatigue ;  in  any  case,  further  and  more  extensive 
tests  must  be  carried  out,  and  upon  adults  as  well  as 
upon  children. 

The  algesiometer  method.  The  increase  of  sen- 
sitivity to  pain,  or  the  magnitude  of  the  pressure  that 
is  necessary  to  arouse  a  sensation  of  pain  (not  a  feel- 
ing of  unpleasantness)   at  a  given  point,  has  also 


42  MENTAL   FATIGUE 

been  taken  by  Vannod  {Fatigue  Intel.)  as  a  meas- 
ure of  fatigue.  A  prick-like  pressure  is  applied  to 
the  skin  by  means  of  an  ^  algesiometer, '  which  is  an 
instrument  closely  similar  to  von  Frey's  hair  esthesi- 
ometer,  and  which  consists  essentially  of  a  fine  point 
and  a  scale  that  indicates  the  pressure  of  the  hand 
upon  the  point,  and  consequently  of  the  point  upon 
the  skin.  In  his  experiments,  Vannod  found  that  at  8 
o'clock,  before  instruction  began,  a  pressure  of  45 
grams  set  up  a  pain  sensation,  whereas  at  10  o  'clock, 
39  grams,  and  at  noon  only  29  grams  sufficed.  Swift 
has  carried  on  similar  tests  in  American  schools,  and 
Yaschide  has  confirmed  Vannod 's  report.  Binet 
{Annee  psychologique,  XI),  however,  reached  di- 
rectly the  opposite  result,  viz.,  that  fatigue  decreases, 
not  increases,  pain  sensitivity  (Cf.  Claparede,  199  f., 
and  Meumann,  II,  109). 

It  must  be  repeated  that  in  all  these  cases,  with  the 
exception  of  these  last — as  to  the  real  nature  of 
which  we  have  as  yet  insufficient  knowledge — what  is 
measured  is  not  so  much  mental  fatigue  itself,  as 
rather  a  mental  activity  that  is  essentially  condi- 
tioned by  the  degree  of  attention  that  is  given  to  it. 
We  are  dealing,  then,  with  a  measurement  of  atten- 
tion, the  reduction  of  which  we  regard  as  the  result 
of  the  work  that  has  been  performed.  But  it  is  evi- 
dent that  the  measure  of  the  attention  applied  to  a 
given  piece  of  work,  or  of  the  mental  energy  dis- 
played in  it,  is  conditioned  not  only  by  the  amount 
of  mental  energy  available  at  the  time,  but  also  by 
other  factors,  such  as  feelings,  moods,  general  dis- 
position, inclination,  and  the  like.  However,  these 
supplementary  factors  are  not  subject  to  regular 


THE   PSYCHOLOGICAL   METHODS  43 

daily  or  weekly  variations  corresponding  with  the 
amount  of  work  done  at  the  time,  but  are  quite  vari- 
able in  their  appearance,  so  that,  as  investigations 
increase  in  number,  they  assuredly  tend  to  be  elimi- 
nated. The  fund  of  mental  energy,  on  the  other 
hand,  is  the  most  important  factor  that  conditions 
attention  and  psychical  activity  in  general,  so  that 
any  reduction  in  it  during  or  after  a  period  of  work 
becomes  very  clearly  and  very  uniformly  evident. 
On  this  fact  rests  the  applicability  of  discriminative 
sensitivity  to  the  measurement  of  fatigue. 

The  measurement  of  fatigue  by  the  measurement 
of  the  duration  of  mental  processes.  We  have  already 
made  reference  to  the  fact  that  the  duration  of  men- 
tal processes  is  affected  by  fatigue.  The  principle 
has  been  turned  to  account  experimentally  by  Keller. 
In  studying  the  development  of  fatigue  during 
lengthy  gymnastic  exercises,  he  had  his  pupils  read 
words  at  a  fast  rate,  and  found  that  the  average  time 
of  reading  was  increased  by  13  per  cent,  for  words 
and  by  16  per  cent,  for  syllables,  in  comparison  with 
the  average  time  in  a  fresh  condition :  even  when  the 
same  words  or  syllables  were  used,  the  time  was  in- 
creased by  10  and  by  9  per  cent.,  respectively.  In  a 
similar  manner,  Lobsien  iVnt.  u.  Erm.)  sought  to  de- 
tect fatigue  by  the  rate  of  reading  and  the  number  of 
errors  committed. 

Following  the  demonstration  by  Axel  Oehrn  {Psy- 
chol. Arbeit  en,  I)  that  speed  of  mental  acti\dties  is 
reduced  by  fatigue,  S.  Bettmann  {Psychol.  Arbeit  en, 
I)  employed  the  more  refined  methods  of  the  labora- 
tory to  determine  the  time  necessary  to  react  to  a 
presented  impression  or  stimulus  with  one  of  two 


44  MENTAL   FATIGUE 

very  simple  movements,  in  accordance  with  a  pre- 
arranged combination  of  stimulus  and  movement — 
in  other  words,  to  measure  the  time  of  the  simplest 
^choice  reaction.'  He  found  that  this  time  was 
longer  when  the  subject  was  fatigued,  and  that  this 
retardation  was  more  evident  after  mental,  than 
after  bodily  fatigue.  Although  Bettmann  has  called 
special  attention  to  the  sensitivity  of  this  method,  it 
does  not  seem,  up  to  now,  to  have  been  employed  fur- 
ther for  the  determination  and  measurement  of 
fatigue,  so  that  we  cannot  say  at  present  whether  or 
to  what  extent  it  is  feasible  for  more  exact  measure- 
ments. In  any  event,  the  fact  that,  in  the  determina- 
tion of  fatigue  by  means  of  computation  and  other 
similar  tests,  the  speed  of  work  increases  at  first,  and 
often  continues  to  increase,  though  the  quality  is  re- 
duced, should  warn  us  to  be  quite  cautious  in  general- 
izing about  the  relation  between  the  speed  of  mental 
acti\dties  and  fatigue. 

The  method  of  test-prohlems  in  the  narrower 
sense.  The  discrimination  of  two  points  on  the  skin, 
the  perception  of  faint  sensory  stimuli,  the  compari- 
son of  the  extent  of  two  movements  and  similar  pro- 
cesses are  all  mental  activities  that  are  used  to  ascer- 
tain how  much  of  mental  energy  remains  after  some 
other  form  of  mental  activity.  The  method  of  test- 
problems  in  the  narrower  sense  is  based  on  the  same 
principle.  In  it,  a  test  is  introduced  during  or  after 
the  mental  activity  that  is  creating  fatigue.  But  this 
test  is  now  far  less  simple,  less  limited  in  its  demands, 
less  dependent  on  physiological  factors  and  more 
akin  to  the  fatiguing  mental  activity  that  it  measures 
than  is  the  test  of  discriminative  sensitivity,  etc.  The 


THE    PSYCHOLOGICAL    METHODS  45 

test-work  consists  cMefly  of  sucli  tests  as  taMng  dic- 
tation, computing,  counting  letters,  and  other  similar 
actiA^ties  which  involve  a  series  of  mental  processes 
of  a  predominatingly  intellectual  character,  like 
those  that  constitute  the  higher  mental  processes  in 
general. 

This  method  had  its  inception  in  the  conmaon  ob- 
servation that  hard  mental  work  renders  us  disin- 
clined and  unfit,  at  first  for  the  kind  of  work  we  are 
doing,  then  for  similar  work,  and  finally  for  any  sort 
of  mental  exertion.  That  is  to  say,  we  are  in  a  state 
of  general  fatigue.  Nevertheless,  we  have  reason 
to  suppose  that  this  general  reduction  of  mental  effi- 
ciency does  not  affect  all  phases  of  mental  activity 
equally,  hut  rather  in  accordance  with  the  degree  of 
similarity — that,  in  other  words,  the  mind  is  the  more 
fatigued  for  a  given  form  of  new  activity,  the  more 
this  new  activity  resembles  the  original  fatigue-pro- 
ducing activity.* 

It  follows  that  these  tests  of  fatigue  that  prescribe 
a  form  of  work  that  is  as  similar  as  possible  to  the 
fatigue-producing  activity,  particularly  to  school 
work,  really  get  at  mental  fatigue  from  more  sides 
than  do  such  tests  as  esthesiometry  and  the  like. 

Still,  they  do  not,  by  any  means,  get  at  it  from  all 
sides,  because  a  form  of  test  that  should  be  fully 
equivalent  to  the  activities  involved  in  studying  and 
in  school  work  generally  would  itself  be  so  com- 
j)]icated  that  it  would  be  impossible  to  evaluate  it  ex- 
actly, especially  to  determine  and  compute  the  errors, 
and  hence  impossible  to  compare  the  different  tests ; 


*The  disputed  question  of  specific  versus  general  fatigue  must 
be  deferred  for  extended  discussion  in  a  subsequent  section. 


46  MEISTTAL   FATIGUE 

moreover,  it  is  impossible  to  devise  absolutely  equiva- 
lent test-problems.  Accordingly,  if  we  want  a  form 
of  test  that  shall  permit  of  ready  quantitative  treat- 
ment, and  that  shall  at  the  same  time  be  exactly 
equivalent  to  the  fatiguing  work,  we  must  simplify 
the  fatiguing  work,  e.  g,,  by  the  use  of  dictation,  sim- 
ple computation,  and  the  like.  By  this  plan,  we  secure 
perfect  comparability  between  the  test-material  and 
the  fatiguing  work;  on  the  other  hand,  we  lose  touch 
with  practical  life,  because  the  mental  fatigue  that 
we  wish  to  measure  is  commonly  the  result  of  a  much 
richer  and  more  elaborate  mental  activity. 

Schoolroom  tests  of  fatigue  seek  a  path  between 
these  two  extremes.  The  younger  a  class  and  the 
simpler  the  mental  work  that  is  required  of  it,  the 
nearer  can  the  test  approximate  to  the  fatiguing 
school  activity.  But  the  more  advanced  the  class  and 
the  more  manifold  and  complex  the  work  that  is  done 
by  it,  the  less  can  the  test  be  made  to  approximate  to 
this  more  elaborate  fatiguing  work. 

The  first  investigator  to  employ  considerable 
amounts  of  work  as  test-materials  for  measuring 
fatigue  was  the  Russian  psychiatrist,  J.  Sikorski. 
He  had  pupils  write  from  dictation  for  a  quarter  of 
an  hour,  both  early  in  the  day,  before  school  work 
began,  and  later  in  the  afternoon,  after  school  work 
was  over.  He  found  33  per  cent,  more  errors  in  the 
second  exercise.  It  is  understood,  of  course,  that 
here,  as  in  other  experiments  of  this  kind,  it  is  not  a 
question  of  errors  that  spring  from  lack  of  knowl- 
edge, but  only  of  errors  that  spring  from  slips  of 
attention.  Naturally,  Sikorski 's  method,  like  the 
first  trial  of  any  such  experiment,  is  susceptible  of 


THE   PSYCHOLOGICAL   METHODS  47 

improvement:  it  served,  however,  to  break  the 
ground,  and  those  who  followed  him,  like  Friedrich 
at  Wiirzhurg  and  Bellei  at  Bologna,  have  learned  how 
to  avoid  his  difficulties.  Yet  there  remains  the  great 
difficulty  of  arranging  material  for  dictation  that 
really  presents  uniform  difficulty  for  the  pupils,  for 
unity  of  the  standard  of  measurement  is  a  prime 
necessity. 

To  circumvent  this  difficulty,  H.  Laser  (Geist. 
Erm.),  following  Burgerstein's  example,  selected 
simple  computation  as  a  test-material.  He  had  his 
subjects,  boys  and  girls  of  the  middle  classes  of  a 
Konigsberg  Bilrgerschule,  perform  easy  examples 
in  addition  and  multiplication  for  10-minute  periods 
and  as  rapidly  as  possible.  The  joeriods  he  arranged 
to  fall  at  the  opening  of  the  morning  session  and  at 
the  end  of  each  one  of  the  five  following  school  hours. 
He  discovered  a  rapid  increase  in  the  total  amount 
of  computation  performed  by  the  several  classes  dur- 
ing the  school  session.  This  increase,  however,  is  to 
be  explained  as  due,  not  to  any  augmentation  of  men- 
tal energy  toward  the  end  of  the  session,  but  partly 
to  the  development,  during  the  work,  of  practice  in 
computing,  and  partly  to  the  overcoming  of  the  men- 
tal inertia  that  prevailed  at  the  outset.  On  the  other 
hand,  the  increasing  fatigue  of  the  classes  found  its 
expression  in  the  increase  in  the  total  number  of 
errors  (except  in  the  final  period)  and  of  corrections 
(made  by  the  pupils  themselves),  and  in  the  decrease 
in  the  number  of  pupils  whose  work  was  without 
error.  These  results  of  Laser  coincide  substantially 
with  those  obtained  by  Burgerstein  by  another  form 
of  computation  test,  to  which  we  shall  refer  later  on. 


48  MENTAL   FATIGUE 

Ebbinghaus  {Neue  Metliode,  etc.)  also  nsed  this 
method,  and  obtained  similar  results.  Computation 
has  been  tried,  likewise,  by  Eichter,  Friedrich,  Kem- 
sies,  Dankwarth,  Teljatnik  and  Bellei.* 

The  query  may,  however,  be  raised  whether  this 
application  of  the  computation  test  for  10  minutes 
or  longer  is  not  unwise,  for,  as  Ebbinghaus  noted, 
computation  develops  a  considerable  practice-effect 
in  a  period  of  this  length,  and  again,  the  computation 
itself  becomes  a  source  of  fatigue.  Moreover,  ennui, 
with  consequent  carelessness  and  loss  of  interest, 
brings  it  about  that  the  quantity  and  quality  of  the 
computation  cannot  be  regarded  as  an  unambiguous 
expression  of  the  fatigue  induced  by  the  school  work 
that  has  just  preceded.  But,  by  both  shortening  the 
duration  and  increasing  the  difficulty  of  the  computa- 
tion exercises,  it  seems  as  if  a  measure  of  fatigue  is 
discovered  for  us  here,  though  one  that  can  be  em- 
ployed only  along  with  others,  because  it  involves 
only  a  specific  and  limited  form  of  mental  activity. 

What  is  called  the  memory  method,  as  used  by  Eb- 
binghaus {Neue  Methode,  etc.),  and  later  on  by  the 
Eussian  experimental  psychologist,  Netschajeff,  by 
Schuyten,  and  by  others,  seems  to  be  less  applicable 
in  the  schoolroom.  In  Ebbinghaus'  experiment, 
series  of  one-syllabled  digits  (the  numbers  1  to  12t), 
arranged  to  supply  two  series  each  of  6,  7,  8,  9,  and 
10  places  (i  e.,  10  series  in  all)  were  read  aloud,  with 
a  single  reading  for  each  series,  at  the  beginning  and 
at  the  end  of  a  school  period.    The  pupils,  who  in- 


*For  methods  and  results  see  also  reference,  p.  24,  note  (Cli.  IX, 
Test  Z^).— Translator. 

fThe  German  term  for  eleven  is  monosyllabic. — Translator. 


THE   PSYCHOLOGICAL   METHODS  49 

eluded  Sexta  to  Untersekunda  forms  [ages  8  to  18] 
of  a  Breslau  Gymnasium  and  some  classes  of  a  higher 
girls'  school,  were  then  asked  to  write  down  each 
series  as  accurately  as  possible.  Fatigue  was  to  be 
indicated  by  the  number  of  errors.  But,  in  almost 
every  case,  the  number  of  errors  decreased  toward 
the  end  of  the  school  session.  Here,  then,  the  effect  of 
fatigue  was  concealed  by  practice,  by  the  confusion 
incident  to  writing  the  digits,  and  perhaps  also  by  the 
method  that  Ebbinghaus  chose  for  computing  the 
errors.  And  even  if  this  method  did  afford  a  fairly 
exact  expression  of  fatigue,  it  would  need,  for  the 
same  reasons  as  were  cited  for  the  computation 
method,  to  be  supplemented  by  some  method  that 
would  afford  contact  with  other  phases  of  mental 
activity,  since  the  retention  of  series  of  one  and  two- 
place  numbers  is  quite  as  limited  and  specific  a  form 
of  work  as  is  long-continued  adding  and  multiplying. 
The  same  thing  might  be  said,  too,  of  tests  of  memory 
for  series  of  words,  as  employed  by  Ritter  and  Tel- 
jatnik,  and  of  memory  for  sentences,  as  employed  by 
Januschke. 

What  has  been  termed  the  ^completion  method' 
was  invented  by  Ebbinghaus  {Neue  Methode,  etc.) 
for  the  same  purpose  of  testing  fatigue.  There  were 
laid  before  the  pupils  prose  texts,  as  nearly  as  pos- 
sible of  the  same  difficulty,  in  which  many  of  the 
words  were  omitted  entirely,  and  in  which  only  por- 
tions of  others,  e.  g.,  some  syllables  or  only  the  first 
letters,  were  given,  and  the  pupils  were  instructed  to 
fill  out  the  gaps  so  as  to  make  sense  and  with  due  re- 
gard to  the  number  of  syllables  demanded.  Five 
minutes  were  allowed.    One  text  was  taken  f  romi  Net- 


50  MENTAL   FATIGUE 

tlebeck's  Description  of  the  Siege  of  Colberg.  A 
single  paragraph  will  suffice  to  illustrate  the  plan. 

Wh . .  Willy  . . .  two  old,  he red 

f  arm-h th  .  yard  .  .  front  ....  The  dan .... 

. . .  were  ....  th. . .  there ;  so  that lo.  . . . 

yellow  instead  of *    The  nature  and  number  of 

the  errors  and  of  the  corrections  were  to  be  taken  as 
an  index  of  fatigue.  The  result  was  not  very  clean- 
cut:  there  appeared  an  increase  in  the  quantity  of 
work  done,  i.  e.,  in  the  number  of  elisions  supplied,  in 
the  upper  classes,  but  a  decrease  in  the  lower  classes. 
Sexta  and  Quinta  [9  to  11  years].  The  quality  of 
work  did,  indeed,  become  poorer  in  all  classes,  al- 
though the  maximal  number  of  errors  was  by  no 
means  made  in  the  last  study  period.  The  decline  in 
quahty  was  also  much  more  rapid  in  the  lower  than 
in  the  higher  classes. 

The  method  is,  of  course,  open  to  improvement. 
Ebbinghaus  is  quite  right,  for  instance,  in  conclud- 
ing after  his  experiment  that  the  time  allowed  for 
supplying  the  elisions  was  too  long.  His  experi- 
ments, it  must  be  remembered,  were  all  preliminary 
experiments,  and,  imfortunately,  the  test  proper 
that  was  to  follow  them  was  never  carried  out. 
Moreover,  despite  Ebbinghaus'  proposals  {Neue 
Methode,  47  f.),  the  most  serious  difficulty  still  re- 
mains— that  it  is  even  less  possible  than  in  the  case  of 
dictations  to  work  out  any  very  large  number  of 
texts  of  equal  difficulty,  or  to  recognize  and  make  due 
allowance  in  computing  results  for  either  these  un- 

*Tliis  example,  from  the  translator's  Manual,  p.  448,  is  substi- 
tuted for  the  German  text.  Blank  forms  for  conducting  this  test 
may  be  purchased  of  0.  H.  Stoelting  Company,  121  North  Green 
street,  Chicago. 


THE   PSYCHOLOGICAL    METHODS  51 

avoidable  differences  in  the  texts  or  for  such  differ- 
ences as  depend  on  the  individuality  of  the  pupils 
tested.*  These  difficulties,  coupled  with  certain  of 
those  that  have  been  cited  in  connection  with  the 
methods  previously  discussed,  will  interfere  with  the 
use  of  the  Ebbinghaus  method  in  extended  school 
tests.  It  has,  moreover,  been  tried  thus  far  only  by 
Bellei,t  though  it  has  the  advantage  over  all  other 
methods  of  appealing  to  quite  varied  phases  of  men- 
tal life,  yet  not,  of  course,  to  all  phases. 

A  more  difficult  form  of  the  completion  method  is 
used  by  some  French  investigators.  They  give  the 
subject  a  number  of  words  which  are  arranged  to- 
gether and  written  down  as  a  whole  in  such  a  form 
as  to  make  sense.  The  method  used  by  Emily  Sharp,1: 
in  which  as  many  sentences  as  possible  are  con- 
structed from  a  limited  number  of  words,  is  of  similar 
kind  (Cf.  G-aupp,  126).  These  methods  have  the  evi- 
dent advantage  that  they  engage  a  considerable  part 
of  the  subject's  mentality,  but  they  have  also  the  de- 
fect that  they  put  at  a  disadvantage  subjects  of  lesser 
ability  and  of  little  practice,  and  that,  furthermore, 
even  when  merely  inserted  as  tests,  they  are  them- 
selves extremely  fatiguing. 

When  these  objections  are  considered,  the  dicta- 
tion and  computation  methods  must,  after  all,  be 


*Cf.  the  criticisms  of  Lobsien,  PM.  Psych.,  II,  365  f.,  and  Binet, 
316  fe. 

fThis  statement  is  not  strictly  accurate.  Ebbinghaus'  method 
has  been  tried  by  Wiersma  (1902),  by  Terman  (1906),  by  Kriiger 
and  Spearman  (1907),  and  with  some  modifications  by  Lipmann 
and  Wertheimer  (1907),  though  only  Wiersma  was  directly  inter- 
ested in  testing  fatigue  by  its  use. — Translator. 

JSee  American  Joiirnal  of  Psychology,  X,  1899,  329-391;  also 
reference,  footnote,  p.  24  (Tests  46  and  47). 


52  MENTAL   FATIGUE 

given  preference  over  the  completion  method,  since 
they  are  simple  methods,  but  nevertheless  have 
fewer  defects.  Especially  are  they  to  be  preferred 
when  their  task  is  made  somewhat  more  difficult,  as 
for  example,  the  form  of  computation  test  employed 
by  Kemsies  {Arheitshygiene  der  Schule,  7),  and  by 
Teljatnik,  in  which  the  computation  is  done  wholly 
mentally,  and  only  the  result  written  down.  This 
plan  has  the  further  advantage  of  reducing  the  physi- 
cal work  of  writing,  and  thereby  lessening  the  chance 
of  introducing  some  bodily  fatigue  in  the  computa- 
tion itself. 

Yet,  the  chance  of  inducing  fatigue  in  this  way 
needs  hardly  to  be  considered  when  dealing  with 
maturer  pupils,  and  especially  with  adults.  With 
such  subjects,  more  difficult  computations  may  be  em- 
ployed with  success,  as  Winch  has  shown  in  the  case 
of  evening  school  pupils,  15  to  27  years  of  age. 

The  advantage  of  easy  administration  and  of  a 
certain  breadth  of  activity — though  not,  of  course, 
of  universality  of  appeal — attaches  also  to  a  method 
used  by  Eitter  {Zeits.,  XXIV,  424  fp.).*  In  this 
(the  cancellation  method),  specified  letters  or  words 
are  to  be  crossed  out  or  cancelled  on  a  given  printed 
text  as  rapidly  as  possible.  The  assignment  might 
be,  for  example,  to  put  a  vertical  mark  through  every 
E  and  r  and  a  horizontal  mark  through  every  form 
of  the  definite  article.t   Onlv  two  minutes  are  allowed 


*This  method  appears,  however,  to  have  originated  in  the  work 
of  Bourdon  {Revue  philosophique,  1895).  Ritter's  article  appeared 
in  1900.  For  a  more  extended  account  of  it  see  my  Manual  of  Men- 
tal and  Physical  Tests,  pp.  254-270. — Translator. 

fin  German  the  article  is  declined,  and  hence  appears  in  several 
different  forms. — Translator. 


THE   PSYCHOLOGICAL    METHODS  53 

for  one  such  test.  The  difficulty  with  this  interesting 
method  lies  in  the  selection  of  texts  that  shall  afford, 
for  a  full  series  of  tests  for  a  day,  not  to  speak  of  a 
week,  an  approximately  equal  distribution  of  the  let- 
ters or  words  to  be  cancelled.*  The  rapid  develop- 
ment of  practice  also  tends  oftentimes,  at  the  begin- 
ning, to  conceal  the  effect  of  fatigue. 

Still  simpler  is  the  copying  method  employed  by 
M.  C.  Schuyten,  the  conductor  of  the  Pedological  In- 
stitute at  Antwerp  {Arch,  de  Psych.,  IV,  and  Paed. 
Jaarh.,  VI,  160  if .) .  The  teacher  writes  on  the  black- 
board a  certain  number  of  combinations  of  the  letters 
a,  e,  %,  0,  u,  r,  v,  n.  The  pupils  have  five  minutes  in 
which  to  copy  them.  The  number  of  errors  and  [self- 
made]  corrections  gives  a  measure  of  attention,  and 
hence  of  the  mental  efficiency  prevailing  at  the  time, 
and  the  variation  in  this  number  at  different  hours 
of  the  day  serves  as  a  basis  for  estimating  the  course 
of  the  fatigue  developed  by  the  day's  work. 

Perhaps  the  most  suitable  method,  both  because  it 
exacts  activities  that  are  neither  too  easy  for  the  sub- 
jects nor  too  difficult  for  evaluation  by  the  experi- 
menter, and  because  it  entails  manifold  forms  of  men- 
tal activity  and  so  does  not  become  monotonous  and 
irksome,t  is  the  combined  method  by  which  Teljat- 
nikj  tested  25  Volksschule  girls,  averaging  9  years  of 
age. 


♦Several  plans  for  meeting  this  difficulty  are  now  available.  See 
Manual,  256-7. — Translator. 

fThe  method,  however,  does  take  considerable  time,  some  20 
minutes,  when  used  for  testing  fatigue,  and  may  thus  itself  become 
a  source  of  fatigue. 

$See  Teljatnik's  report  of  his  own  researches  as  prepared  for 
Burgerstein's  Handhuch  der  Schulhygiene,  2d  ed.,  pp.  462  ff. 


54  MENTAL   FATIGUE 

Every  experiment  was  subdivided  into  four  parts. 
The  first  of  these  tested  attention.  The  girls  were 
asked  to  count  the  letters  in  each  of  the  first  five  lines 
of  a  page  of  their  readers,  and  to  write  down  the  five 
sums  upon  a  sheet  of  paper.  They  had  next  mentally 
to  add,  or  to  substract,  several  pairs  of  two-place 
numbers  that  were  written  for  them  on  the  black- 
board, and  to  write  the  answers  on  their  papers.  To 
test  observation,  or  direct  retention,  as  Meumann 
likes  to  term  it  (or  the  capacity  for  immediate  repro- 
duction, as  I  prefer  to  say — Geddchtnis,  129),  either 
six  one-to-three  syllable  words  or  four  one-to-two 
place  numbers  were  used.  These  were  either  recited  by 
the  teacher  and  then  repeated  by  the  pupils  in  concert, 
or  were  written,  shown,  and  then  erased;  in  either 
case,  the  pupils  had  immediately  to  write  down  as 
many  of  them  as  they  could  remember.  Recollection, 
or,  more  accurately,  recognition,  was  tested  by  hand- 
ing to  the  pupils  sheets  containing  100  words  and  50 
figures,  among  them  those  that  had  been  previously 
used  in  the  test  of  immediate  reproduction,  and  ask- 
ing them  to  underline  the  words  or  numbers  that  they 
had  heard  (or  seen).  Since,  however,  every  act  of 
recognition  is  conditioned  by  two  factors — the  dis- 
position (tendency)  and  the  incitement  of  the  dis- 
position (Cf.  Oifner,  Geddchtnis,  108) — it  follows 
that  the  recognition  can  fail,  either  on  account  of  in- 
sufficient strength  of  incitement,  despite  a  very  strong 
tendency,  or  on  account  of  a  feeble  tendency  (poor 
impression),  despite  a  strong  incitement.  These  two 
factors,  then,  must  be  considered  independently  of 
one  another,  because  it  is  not  certain  whether  the  two 
are  equally  affected  by  fatigue. 


THE   PSYCHOLOGICAL   METHODS  55 

This  four  fold  test  was  applied  at  the  beginning,  at 
the  end  and  twice  in  the  course  of  a  school  session 
that  ran  from  9  to  2  o  'clock,  and  that  was  broken  by 
one  long  and  several  short  pauses.  By  a  special 
method  of  treating  the  data,  Teljatnik  derived  from 
the  four  forms  of  tests  an  average  value  which  he 
termed  an  ^4ndex  of  general  capacity  for  work,"  and 
which  he  used  to  measure  mental  fatigue,  together 
with  the  effect  of  pauses  in  the  school  work  (some 
occupied  in  games,  some  spent  in  absolute  rest),  and 
other  similar  phases  of  the  problem. 

We  may,  perhaps,  think  of  better  specific  tests  than 
these ;  we  may  criticize  the  plan  of  combining  values 
derived  from  the  separate  tests  into  a  single  one  that 
conceals  the  differences  in  the  development  of  the 
component  factors;  nevertheless,  Teljatnik's  method 
seems  to  be  the  one  that  has,  thus  far,  made  the  most 
manifold  appeal  to  mental  life,  and  at  the  same  time 
the  one  that  is  characterized  by  the  greatest  ease  of 
administration  and  evaluation. 

If  we  take  a  general  survey  of  these  experiments 
with  various  forms  of  tests,  from  the  method  of 
Griesbach  to  that  of  Teljatnik,  we  see  that,  despite 
many  defects  that  may  perhaps  be  remedied,  and 
many  difficulties  that  are  inevitable,  they  supply  us, 
beyond  any  doubt,  with  serviceable  average  values 
(particularly  when,  by  frequent  repetition,  the  er- 
rors are  gradually  eliminated  by  the  law  of  large 
numbers),  and  afford  reliable  information  as  to  the 
effect  and  the  degree  of  fatigue,  and  that  they  may, 
therefore,  be  significant  for  us  in  the  regulation  of 
our  work.  These  methods  are  also,  so  far  as  we  can 
see,  the  only  ones  that  can  at  the  present  time  be  ap- 


56  MENTAL   FATIGUE 

plied  in  schools,  and  so  be  of  direct  ntility  for  prac- 
tical schoolroom  service. 

Their  theoretical  value  is,  nevertheless,  limited. 
These  forms  of  test-work  do  not  permit  us  to  follow 
the  course  of  fatigue  accurately  and  step  by  step, 
else  the  fatiguing  work  would  be  so  frequently  in- 
terrupted by  the  inserted  test-work  that  the  effect  of 
the  former  would  be  concealed,  since  the  test-work 
itself  would  induce  a  high  degree  of  fatigue. 

Method  of  Continuous  Work 

It  was,  therefore,  a  happy  thought  to  use  the 
fatiguing  work  as  test-work,  to  observe  uninterrupt- 
edly the  changes  in  quantity  and  quality  of  perform- 
ance effected  by  the  fatigue-work,  and  to  take  these 
changes  as  an  index  of  the  fatigue  or  of  the  decrease 
of  mental  efficiency  caused  by  the  work. 

In  this  method,  then,  it  is  the  continuous  work  it- 
self, not  bits  of  test-work  applied  at  different  times, 
that  indicates  to  what  extent  and  how  rapidly  mental 
efficiency  is  affected  by  the  work. 

It  is  clear  that  any  continuous  mental  work  of  a 
complex  nature,  e.  g.,  the  reading  and  assimilation 
of  a  paragraph  from  Kant's  Critique  of  Pure  Rea- 
son, the  working  out  of  mathematical  problems  or 
the  prosecution  of  botanical  observation  and  experi- 
ments— that  such  complex  work  would  exclude  the 
possibility  of  a  detailed  and  exact  determination  of 
the  effect  of  fatigue.  For  this  purpose  such  simpler 
mental  processes  must  be  selected,  processes  that  are 
not  only  characterized  by  a  high  degree  of  uniform- 
ity, but  that  also  permit  the  quick  recognition  of  the 
effect  of  fatigue.    The  course  of  such  an  activity,  e.  g., 


THE   PSYCHOLOGICAL   METHODS  57 

two-honr  adding  of  one-place  numbers,  may  also  be 
shown  in  graphic  form.  A  horizontal  line  is  divided 
into  24  parts,  each  one  of  which  (for  the  two-hour  test 
just  mentioned)  accordingly  represents  a  five-minute 
period.  The  additions  made  in  each  of  the  five-min- 
ute periods  are  then  indicated  by  a  line  of  the  proper 
length  erected  as  a  perpendicular  to  the  base-line. 
By  joining  the  tips  of  these  perpendiculars,  we  ob- 
tain a  line  that  is  known  as  a  curve  of  work. 

This  method  was  used  for  the  first  time  by  the 
Austrian  schoolman,  L.  Burgerstein  {Arheitskurve 
einer  ScMilstunde),  when,  in  1891,  he  studied  the 
course  of  fatigue  within  a  single  school  hour.  He 
caused  his  pupils,  boys  aged  11  to  13  years,  to  per- 
form easy  examples  in  addition  and  multiplication,  in 
periods  of  10  minutes  each.  A  pause  of  five  minutes 
was  introduced  after  each  of  these  work-periods. 
In  this  case,  he  found  that,  on  the  average,  the  num- 
ber of  examples  performed  increased  from  one  quar- 
ter of  an  hour  to  the  next,  perhaps  on  account  of  aug- 
menting practice,  or,  toward  the  end,  from  anxiety 
of  the  boys  lest  they  should  not  be  ready,  or  because 
at  the  start  they  were  working  under  an  inhibition 
that  was  only  overcome  by  the  work  itself.  There 
were,  however,  more  errors  and  corrections  made  as 
the  work  went  on. 

In  a  similar,  though  much  less  extended  experi- 
ment, using  forms  of  Latin  verbs  as  test-material, 
H.  Merian-Genast,  in  the  Gymnasium  at  Jena 
(Cf.  Eichter  in  Lehrprohen,  XLV,  8,  note),  obtained 
similar  results.  Tliis  method  is  feasible  for  school 
use. 

So  far  as  Burgerstein 's  results  are  concerned,  we 


58  MENTAL  FATIGUE 

may  call  attention  to  Ms  rather  questionable  com- 
putation of  the  errors  (Binet  and  Henri,  300 ;  Ebbing- 
haus,  24),  and  we  should  note  that  the  results  can- 
not be  interpreted  without  qualification  as  an  indica- 
tion of  the  fatigue-eifect  of  an  ordinary  or  normal 
school  hour.  For  school  work  is  hardly  ever  so  ex- 
tremely uniform  in  character,  nor  does  it  ever  require 
uniformly  sustained  attention  of  the  sort  exacted  in 
these  computations,  which,  moreover,  were  carried 
on  under  stress  of  maximal  speed.  This  criticism 
has  already  been  urged,  and  with  right,  by  Eichter, 
Uhlig  and  others,  particularly  against  Kraepelin's 
work.  Demands  like  those  in  these  tests  are  made 
upon  the  pupil  at  most  only  when  he  is  doing  'sight 
work'  or  school  tasks,  or  when  he  is  actually  being 
questioned,  and  the  other  pupils  are  then  less  actively 
engaged.  Moreover,  continuous  computation  of  an 
hour's  duration  is  a  monotonous  work  of  a  kind  such 
that,  after  a  short  time,  ennui  or  aversion,  or  at  least 
indifference,  appears,  and  this  must  be  overcome  by 
plucking  up  fresh  courage  for  attentive  work :  these 
circumstances  are  naturally  fatal  to  uniform  work 
of  sustained  quality,  while,  despite  fatigue,  the  speed 
of  the  work  is  increased  by  practice  (Cf.  Ebbinghaus, 
6;  Binet  and  Henri,  302).  But  even  if  these  difficul- 
ties did  not  exist,  we  should  still  be  unable,  as  we  have 
already  pointed  out,  to  infer  positively,  and  as  a  mat- 
ter of  course,  that  fatigue  followed  the  same  line  of 
development  in  other  forms  of  mental  work  as  it  does 
in  the  case  of  computation.  That  must  first  be 
proved.  For  these  reasons,  Burgerstein's  results, 
like  those  obtained  with  his  method  by  others,  e.  g., 
by  Marion  Holmes  (Pedagogical  Seminary,  HI)  with 


THE   PSYCHOLOGICAL   METHODS  59 

American  students,  have  in  every  case  only  a  limited 
significance,  namely,  for  that  particular  work  ujjon 
which  they  were  based. 

Within  this  limited  field,  however,  the  method  of 
continuous  work  undoubtedly  affords  information  of 
value  so  far  as  it  applies,  and  its  usefulness  for  school 
practice  becomes  greater  in  proportion  as  the  task 
used  for  experimentation  resembles  the  tasks  of  the 
schoolroom  itself.  The  best  plan  is  simply  to  use 
school  work  itself  as  the  basis,  though  this,  to  be  sure, 
can  be  done  only  in  the  earlier  grades.  This  plan 
has  been  tried  by  L.  Hopfner  {Zeits.^  VI,  194  if.), 
who  conducted  a  dictation  test  with  a  class  of  boys 
of  the  average  age  of  9  years.  This  test  consisted  of 
19  sentences,  each  one  containing  approximately  30 
letters.  Each  sentence  was  read  to  the  class  once, 
then  repeated  once  by  a  single  pupil,  and  finally  re- 
peated by  the  entire  class.  After  this,  the  children 
were  required  to  write  the  sentence  from  memory. 
The  work  in  this  way  took  two  hours  in  all.  Hopfner 
discovered  a  general,  though  very  irregular  increase 
in  the  number  of  errors  from  sentence  to  sentence. 
His  psychological  analysis  of  the  errors  showed  that 
the  longer  the  dictation  continued  (and  hence  the 
more  wearied  the  pupils),  the  more  prevalent  became 
errors  due  to  the  displacement,  by  colloquial  speech, 
of  the  literary  phrases  learned  in  the  classroom.  It 
is,  then,  the  later  acquired  bits  of  knowledge,  the 
more  recent  associations,  that  fail  first — that  first 
show  the  effect  of  fatigue — ^while  the  older  acquisi- 
tions, the  words,  grammatical  forms  and  expressions 
of  colloquial  speech  that  have  been  learned  earlier, 
and  hence  much  oftener  used — in  short,  the  older  as- 


60  MENTAL   FATIGUE 

sociations — are  thereby  brought  into  function  as  sub- 
stitutes for  them. 

The  advantage  of  Hopfner's  method  over  that  of 
Burgerstein  consists  in  the  fact  that  in  it  a  regular 
school  activity  has  been  studied  for  its  fatigue-effect. 
And  two  further  points  of  advantage  are  that,  since 
a  real  test  is  in  operation,  the  pupils,  of  their  own 
accord,  exert  their  attention  to  the  utmost — indiffer- 
ence and  negligence  cannot,  therefore,  enter  as  dis- 
turbing factors — and  that  efficiency  cannot  be  so 
markedly  augmented  by  practice  during  the  test,  as 
is  so  plainly  the  case  with  computation-work.  There 
is,  to  be  sure,  one  source  of  trouble  even  in  this  test, 
viz.,  the  task  of  securing  material  for  dictation  that 
shall  offer  equal  difficulty  throughout. 

The  method  of  continuous  work  has  been  used  with 
special  success  by  Kraepelin.  In  addition  to  the 
counting  of  letters,  reading,  and  the  committing  to 
memory  of  series  of  digits  and  syllables,  he  has 
favored  the  use  of  the  method  of  the  continuous  ad- 
dition of  one-place  numbers,  because  adding  has  the 
merit  of  being,  after  all,  one  of  the  higher  forms  of 
mental  activity,  while  at  the  same  time  it  is  psycho- 
logically far  more  uniform  than  other  mental  activ- 
ities. Moreover,  verbal  imagery  and  articulatory 
movements  play  a  relatively  minor  role  in  it.  Kraepe- 
lin has  worked  out  a  simple  procedure  for  this 
method.  The  subject  is  required  to  add,  for  a  long 
time  (sometimes  several  hours),  numbers  printed  in 
vertical  columns  in  a  specially  prepared  note-book.* 
Whenever   the    sum   exceeds    100,    the   hundred   is 

*American  readers  may  purchase  such  prepared  forms  of  C.  H. 
Stoelting  Company,  121  North  Green  street,  Chicago. — Translator. 


THE  PSYCHOLOGICAL   METHODS  61 

dropped,  and  tlie  remaining  units  are  carried  on  for 
further  additions.  A  signal  bell  rings  every  five 
minutes.  As  soon  as  the  subject  hears  it,  he  makes 
a  mark  after  the  last  digit  that  he  has  added.  By 
this  means  it  is  easy  to  ascertain,  after  the  experi- 
ment is  finished,  just  how  many  digits  have  been 
added  by  each  subject  in  each  five-minute  period 
(Kraepelin,  Geistige  Arbeit^  4th  ed.,  8).  This  form 
of  the  method  of  continuous  work  is,  to  be  sure,  ill- 
adapted  for  use  in  the  school,  as  Kraepelin  himself 
admits  {V eb erhiir dung sf rage,  13),  but  he  and  his 
followers  have,  by  its  exploitation,  done  pioneer  serv- 
ice in  the  investigation  of  fatigue. 


RESULTS 

Various  factors  in  addition  to  fatigue,  that  de- 
termine efficiency. 

To  Kraepelin  and  liis  followers  we  are  primarily 
indebted  for  the  insight  that  we  possess  into  the 
course  of  long-continued  mental  work.  And  this 
brings  us  to  discuss  the  results  of  the  investigation 
of  fatigue. 

These  investigations  have  shown  that  there  are 
several  factors,  several  psychophysical  phenomena, 
that  are  more  or  less  commonly  present  in  this  kind 
of  work;  that  these  phenomena  are  consequences, 
just  as  fatigue  is  a  consequence,  of  persistent  mental 
work,  and  that  they,  too,  influence  the  outcome  of  the 
work,  influence  our  performance.  Their  influence  is 
however,  largely  opposite  to  that  of  fatigue,  so  that 
they  reduce  or  cancel  the  fatigue-effect,  in  part,  and 
render  it  for  a  time  imperceptible.  These  same  influ- 
ences are  also  operative  in  muscular  work  (Oseretz- 
kowsky),  and  must,  if  we  would  avoid  a  false  inter- 
pretation of  the  results,  be  kept  constantly  in  mind 
in  all  measurements  of  fatigue  or  measurements  of 
work  done. 

Practice.  In  the  first  place,  there  is  practice. 
Whenever  we  continue  or  repeat  an  activity,  the  con- 
sequence is  that,  to  a  certain  extent,  the  activity  is 
carried  out  progressively  more  easily,  i.  e.,  with  a 

62 


EESXJLTS  63 

lesser  expenditure  of  energy,  with  a  lesser  degree  of 
attention,  and  also  both  more  speedily  and  more 
accurately,  i.  e.^  with  fewer  mistakes  and  more  eco- 
nomically, in  that  it  constantly  comes  nearer  the  way 
we  wish  it  to  go  to  accomplish  the  result  that  we  de- 
sire. Although  the  work  done  should  relatively  soon 
suffer  quantitative,  or  at  least  qualitative  impairment 
on  account  of  the  gradual  rise  of  fatigue  due  to  the 
consumption  of  the  available  supply  of  psychophysi- 
cal energy  and  to  the  fatigue-substances,  we  soon 
find,  on  the  contrary,  a  distinct  and  fairly  persistent 
augmentation,  both  quantitative  and  qualitative,  of 
the  work  done.  We  learn,  while  we  are  working,  to 
master  our  tasks  better:  after  a  short  period  of 
work,  often,  in  fact,  after  a  few  minutes,  we  do  arith- 
metical work  more  accurately,  and  particularly  more 
rapidly  than  we  did  when  we  began.  This  process  of 
progressive  improvement  of  performance  we  may 
term  the  concurrent  practice-effect,  and  the  amount 
by  which,  in  a  specified  time,  the  performance  excels 
the  initial  performance,  we  may  term  the  concurrent 
practice- gain,  or  the  practice-result. 

This  practice-effect  does  not,  as  one  might  be  in- 
clined to  expect,  increase  in  proportion  to  the  dura- 
tion of  the  activity  that  is  being  practiced,  but  is 
greatest  at  the  beginning,  and  becomes  smaller  and 
smaller  as  the  activity  continues,  most  probably  just 
in  consequence  of  fatigue.  If  the  work  be  divided 
into  a  number  of  sections,  each  section  will  be  found 
to  have  its  practice-result  or  practice-effect,  but  it 
will  be  less  from  section  to  section.*    Yet,  the  per- 

*Cf.  in  this  connection  my  discussion  of  the  significance  of  repe- 
titions for  impression  (Das  Geddchtnis,  esp.  pp.  47-59). 


64  MENTAL   FATIGUE 

formance  will  still  show  improvement  until  fatigue 
tips  the  scales  against  it,  so  that  the  work  done  is 
more  and  more  reduced,  at  first  qualitatively  and 
then  quantitatively,  until,  as  the  feeling  of  fatigue 
grows  progressively  clearer  and  stronger,  it  finally 
falls  below  the  level  at  which  it  started.  Now,  the 
total  practice-result  of  these  several  periods  of  work 
is  not  a  permanent  possession  that  remains  as  large 
as  it  was  when  it  was  set  aside ;  on  the  contrary,  the 
condition  of  practice  begins  to  wane  as  soon  as  the 
practicing  activity  stops.  And,  again,  this  process 
is  not  proportional  to  the  time  elapsed,  but  is  rapid 
at  first,  then  slower  and  slower,  and  often  the  state  of 
practice  remains  perceptible  for  a  surprisingly  long 
time  (Cf.  Offner,  103  ff.).  This  residual  skill,  this 
practice-gain  that  persists,  can  be  recognized  in  the 
facilitation  of  the  activity  that  it  brings  about  when 
the  activity  is  resumed  at  some  later  time,  i.  e.,  in  the 
qualitatively  and  quantitatively  better  performance 
of  practiced,  as  contrasted  with  unpracticed  work. 

It  is  with  this  persisting  practice-result  that  school 
instruction  has  ]3rimarily  to  do. 

Both  these  forms  of  practice-result,  moreover,  are 
the  more  evident  the  less  practiced  we  still  are  in  the 
activity,  and  the  less  evident  the  more  frequently 
we  have  had  an  opportunity  to  exercise  the  activity 
(Cf.  in  this  connection,  Offner,  Das  Geddchtnis,  50 
ff.).  And  finally,  there  comes  a  time  when,  even  if 
fatigue  is  not  present,  there  is  no  further  practice 
result,  neither  of  concurrent  nor  of  persisting  prac- 
tice :  this  is  the  moment  of  maximal  practice. 

Habituation.  Hand  in  hand  with  practice  goes 
habituation.    We  cease  to  be  struck  with  the  novelty 


EESULTS  65 

or  peculiar  character  of  the  work.  Many  a  bit  of 
work  that  was  distasteful  at  the  outset  loses  its  char- 
acter of  unpleasantness.  Ideas  foreign  to  the  task 
become  fewer  and  fewer,  and  we  are  able  to  give  our- 
selves over  to  our  activity  with  more  and  more  atten- 
tion.   But  maximal  habituation  is  soon  attained. 

This  shows  us  how  we  can  exclude,  at  least  for  ex- 
perimental purposes,  these  effects  of  practice  and 
habituation,  and  so  remove  an  obstacle  to  the  deter- 
mination of  fatigue.  In  order  to  observe  fatigue,  we 
can  evidently  select  just  those  mental  activities  in 
which  we  have  become  so  trained  by  extended  prac- 
tice that  no  further  increase  of  efficiency  can  be  had 
during  the  work — such  activities,  for  example,  as 
counting  or  very  simple  computation,  particularly  if 
they  have  been  brought  up  to  the  highest  attainable 
degree  of  efficiency  by  a  period  of  special  practice. 
Baade  (39,  107),  however,  maintains  that  complete 
elimination  of  the  influence  of  practice  is  at  present 
impossible,  and  that  its  exact  computation  is  scarcely 
more  to  be  expected.  But  we  can  partly  avoid  the 
practice-error  by  constant  change  of  the  subjects,  so 
that  at  least  no  permanent  practice-gain  shall  de- 
velop in  any  of  them. 

Warming-up  (Anlaiif).  Once  again,  in  tasks  such 
as  we  are  considering,  the  work  done  is  by  no  means 
at  its  maximum  at  the  very  beginning,  but  reaches 
its  best  output  both  qualitatively  and  quantitatively 
some  time — usually,  of  course,  a  short  time — after 
the  start.  This  is  a  matter  of  every-day  observation. 
We  make  use  of  such  expressions  as:  ^^We  haven't 
got  into  the  game  yet ;"  ^^  We  must  get  into  the  spirit 
of  the  work ; ' ' ' '  We  must  get  warmed  up  first ; "  ^  ^  The 


66  MENTAL  FATIGUE 

machine  must  settle  down  to  work/'  This  stage  we 
may  term  'warming-up.'  It  is  a  stage  that  is  passed 
quickly  by  some  persons,  but  takes  more  time  for 
others.  Children,  it  may  be  added,  take  longer  than 
adults  to  settle  down  to  a  new  piece  of  work  (Meu- 
mann,  II,  5  f.).  The  stage  is  particularly  long  if  we 
have  been  previously  occupied  in  some  other  form  of 
interesting  work.  But  when  we  are  once  properly 
warmed  up,  when  we  once  have  ourselves  in  trim, 
then  we  'turn  out'  results  with  ease — then  is  the 
time  when  we  are  doing  our  best  work. 

Swing  or  fitness  for  worlc.  Henceforth  the  work 
takes  full  possession  of  us.  We  are  completely 
'held'  by  it,  or  we  find  ourselves  in  a  condition  of 
full  'swing'  (Anregung),  as  E.  Amberg  {Psychol. 
Arbeit  en,  I,  373  ff.),  Kraepelin  and  his  school  term 
this  mental  condition,  or  in  a  condition  of  complete 
'fitness  for  work'  (Arheitshereitschaft),  as  Meu- 
mann  in  particular  prefers  to  call  it.  It  appears 
now  that,  as  in  the  case  of  fatigue,  so  here  in  the  case 
of  swing,  we  must  distinguish  between  a  general  and 
a  special  form  of  the  condition.  Anyone  knows  that 
a  short  walk  in  the  morning  puts  us  into  the  mood 
for  work,  into  a  readiness  for  any  kind  of  work,  more 
quickly  than  if  we  betook  ourselves  directly  from  the 
breakfast  table  to  the  work.  Thus,  Axel  Key  found 
nothing  but  good  results  for  his  pupils  when  they 
walked  one  to  two  kilometers  [half  a  mile  to  a  mile] 
to  school.*  I  have  noted  in  my  own  case  that,  after 
teaching  from  8  till  9,  I  feel  much  more  disposed  to 

*However,  walking  to  school  from  a  longer  distance  or  a  long 
trip  by  rail  is  fatiguing,  and  produces  a  noticeable  effect  upon 
mental  efficiency,  as  Wagner  has  clearly  shown  by  esthesiometric 
tests. 


EESXJLTS  67 

enter  upon  an  activity  of  quite  another  character  than 
if  I  had  spent  this  hour  at  home  in  the  ordinary  lazy 
way.  Hence,  the  strenuous  mental  activity  demanded 
for  the  teaching,  like  the  activity  of  the  walk,  brings 
about  a  disposition,  a  fitness,  for  every  kind  of  activ- 
ity— ^brings  one  generally  into  swing. 

If,  thereafter,  we  settle  down  at  some  particular 
new  activity  and  get  well  into  the  work,  there  de- 
velops along  with,  and  on  account  of,  our  activity  a 
special  swing  for  this  particular  activity.  It  is  this 
condition  that  Kraepelin  and  other  investigators 
have  in  mind  when  they  speak  of  swing  and  loss  of 
swing.  General  fitness  is  a  condition  that  is  termi- 
nated only  by  fairly  long  intervals  of  rest,  for  in- 
stance, by  a  long  noon-recess,  by  an  afternoon  nap, 
and  particularly  by  a  night's  sleep;  special  fitness, 
however,  is  naturally  terminated  by  a  change  of 
work,  or  even  by  brief  pauses.  If,  for  example,  the 
work  be  interrupted  by  so  short  a  time  as  5  or  10 
minutes  only,  our  special  fitness  suffers  at  once  from 
the  interruption,  and,  of  course,  the  effect  is  the 
greater  the  longer  the  interruption.  It  hardly  needs 
to  be  said  that  this  deleterious  effect  is  much  more 
noticeable  if  the  pause  is  not  a  rest-pause,  but  occu- 
pied in  some  other  form  of  mental  work.  Hence, 
even  in  the  case  of  tasks  in  which  we  are  maximally 
practiced,  and  in  which,  therefore,  there  is  no  ques- 
tion of  a  loss  of  a  practice-effect  for  the  acti\ity  with 
which  we  are  working — e.  g.,  very  simple  problems 
in  adding — even  in  such  a  case,  the  introduction  of  a 
pause  that  we  might  expect  to  bring  about  an  im- 
provement in  our  performance  (because  it  indicates 
recuperation  and  some  reduction  of  the  effect  of 


68  MEITTAL   FATIGUE 

fatigue)  is  more  apt  to  have  the  contrary  efect. 
That  is,  when  we  first  resume  the  activity  in  question, 
our  performance  is  not  infrequently  worse.  Of 
course,  if  there  is  no  considerable  degree  of  fatigue 
present,  this  lessened  efficiency  does  not  last  very 
long.  We  shall  come  back  again  to  this  matter  of 
the  loss  of  swing  when  we  discuss  the  problem  of 
pauses. 

Spurt.  Now,  it  is  by  no  means  always  the  case  that, 
in  sliifting  from  one  task  to  another,  our  initial  per- 
formance with  the  new  task  is  by  loss  of  swing  in- 
ferior to  our  performance  in  the  work  we  had  just 
left.  Often,  on  the  contrary,  the  new  work  starts  off 
considerably  better,  even  though  the  previous  work 
had  left  us  quite  fatigued,  as  in  general  we  often  note 
that  the  very  first  stages  of  any  work  yield  strikingly 
good  results.  Here,  then,  we  come  upon  yet  another 
new  factor.  The  explanation  of  this  outcome,  which 
differs,  as  is  evident,  from  what  we  have  described 
heretofore,  is  to  be  sought  in  the  effect  of  novelty. 
This  factor,  it  is  to  be  noted,  has  an  inhibitory  effect 
upon  many  persons,  but  affects  others,  on  the  con- 
trary, as  a  spur  and  stimulant,  making  an  especially 
strong  appeal  to  their  attention — the  stimuhis  of 
novelty  is  a  matter  of  common  knowledge — and 
bringing  about  the  release  of  an  exceptional  amount 
of  psychophysical  energy.  Following  Kraepelin  and 
his  school,  we  speak  of  such  a  release  of  an  excep- 
tional amount  of  energy  as  a  ^ spurt'  {Antrieb), 
terming  it  an  'initial  spurt'  if  it  develops  at  the  be- 
ginning of  the  work,  or  a  ^ spurt  of  change'  if  at  the 
beginning  of  some  new  and  different  form  of  work. 

As,  in  this  instance,  the  spurt  springs  from  the 


EESULTS  69 

stimulus  of  novelty,  so  it  disappears  as  soon  as  this 
stimulus  ceases — a  condition  of  affairs  that  ordi- 
narily comes  to  pass  in  a  short  time  and  with  special 
and  noticeable  quickness  if  we  have  been  fatigued  by 
the  previous  work.  Accordingly,  a  drop  in  the  curve 
of  performance  can  be  plainly  made  out,  even  quite 
soon  after  the  beginning  of  an  activity — at  a  time 
when  fatigue  is  still  out  of  the  question.  This  drop, 
it  is  true,  lasts  but  a  very  short  time.  Then  the  curve 
rises  again,  at  first  quickly,  until  the  condition  of 
swing  is  fully  developed,  and  afterwards  more  slowly, 
in  consequence  of  the  practice-eif ect.  After  a  certain 
time,  which,  of  course,  varies  with  the  kind  and  dura- 
tion of  the  work,  with  individual  capacity,  and  with 
the  prevailing  mood,  the  performance  falls  off,  both 
in  quality  and  quantity,  if  fatigue  gradually  exerts 
its  baneful  influence,  and  if  the  favorable  effect  of 
practice  is  nullified.  But  this  is  by  no  means  always 
the  case ;  much  oftener  the  course  of  work  is  other- 
wise. We  can  become  more  and  more  absorbed  in  our 
work,  particularly  if  it  be  not  monotonous ;  our  inter- 
est comes  back  again,  as  we  say — or,  what  amounts 
to  the  same  thing  in  this  instance,  our  attention,  our 
expenditure  of  energy — and  hence  our  achievements 
recover  their  former  level.  In  this  manner,  the  effect 
of  fatigue  may  be  compensated  for  a  time. 

However,  it  is  possible  that  quite  the  contrary 
phenomenon  may  occur.  It  may  happen  that  the 
work,  having  now  lost  the  stimulus  of  novelty,  may 
at  once  become  tedious;  that  interest,  or,  more  ex- 
actly, attention,  may  quite  disappear,  so  that  finally 
we  work  reluctantly.  In  this  event,  our  performance, 
which  already  suffers  somewhat  from  fatigue,  nat- 


70  MENTAL   FATIGUE 

urally  falls  off  considerably,  particularly  in  quality. 
And  the  reduction  in  efficiency  is  much  greater  than 
if  fatigue  alone  were  operative.  But  if,  perchance, 
we  recover  ourselves  in  consequence  of  a  some  en- 
couraging word,  or  a  rebuke  or  some  similar  in- 
fluence, then  our  performance  once  more  shows  a 
gain  in  quantity,  and  even  more  in  quality.  Soon, 
however,  fatigue  again  asserts  its  sway,  and  this  shift 
of  efficiency  may  be  repeated  several  times,  until  at 
last  fatigue  takes  full  possession  of  us,  and  the  qual- 
ity and  scope  of  our  work  is  reduced  to  a  minimum. 
Except  that,  if  we  note  that  we  are  nearing  the  end 
of  our  work,  this  circumstance  often  operates  as  yet 
another  and  final  stimulating  and  encouraging  factor. 
This  phenomenon  is  known  as  the  ^terminal  spurt' 
(Schlussantrieh),  and  its  effect  is  to  improve  our  per- 
formance, just  as  horses  step  out  better  when  they 
know  that  they  are  returning  to  their  stable.  If,  on 
the  other  hand,  we  plan,  so  to  speak,  to  work  without 
stopping,  i.  e.,  with  a  firm  resolution  not  to  desist, 
but  spur  ourselves  on  and  ever  force  ourselves  to 
fresh  exertion,  then  there  comes  a  time  when  our 
ability  to  work  is  completely  exhausted ;  we  collapse 
utterly,  and  hardly  ever  without  doing  some  grave 
injury  to  our  health. 

It  is  evident  that  it  is  thew;i??,in  different  forms  and 
degrees,  manifested  as  rising  and  falling  attention 
or  interest,  as  indifference  and  recovery — whether  it 
springs  from  newly-awakened  sense  of  duty  or  from 
the  sight  of  the  approaching  and  long-wished-f or  end, 
or  from  fear  of  not  being  ready — it  is  the  will  that  in 
these  cases  is  affecting  the  course  of  the  work,  and 
that  is,  with  more  or  less  success,  counteracting  the 


EESULTS  71 

effect  of  fatigue.  What  is  thus  demonstrated  within 
the  narrow  bounds  of  experimental  investigation  is, 
moreover,  a  phenomenon  with  which  we  are  all  well 
acquainted. 

The  traveler  who  has  reached  the  top  of  a  moun- 
tain in  an  exhausted  condition,  and  who  has  hardly  a 
wish  but  for  rest,  forgets  his  weariness  all  in  a  mo- 
ment if  he  meets  some  of  his  best  friends,  or  if  he 
spies  some  rare  and  long-sought  plant.  Or  perhaps 
he  finds  that  he  has  taken  the  wrong  road.  The  ap- 
proach of  night,  the  loneliness  of  a  totally  unknown 
region,  the  fear  of  meeting  with  some  accident,  may 
so  excite  him  that  he  feels  no  trace  of  weariness,  that 
he  seems  to  be  filled  anew  with  a  vigor  and  an  elas- 
ticity that  astonish  him.  He  hurries  on  with  marve- 
lous speed  and  endurance  until  he  finally  thinks  he 
has  found  the  right  road.  Then,  indeed,  weariness 
sweeps  over  him  with  twofold  intensity,  because  his 
fear  no  longer  spurs  him  on. 

The  will,  it  would  appear,  then,  puts  at  our  dis- 
posal extra  mental  power.  Not  that  it  creates  it, 
simply  that  it  releases  an  already  existing  capital, 
that  it  opens  the  storehouse  once  more  and  takes  out 
what  the  organism  needs  for  the  work  of  the  moment. 

But  this  process  reduces  the  supply  of  energy,  for 
it  is  not  the  will  that  furnishes  the  energy,  but  the 
substances  taken  up  and  worked  over  by  the  organ- 
ism. This  is  shown  directly  by  the  proportionately 
greater  reduction  of  performance  and  the  propor- 
tionately greater  need  of  nutrition  and  rest  that  fol- 
low the  expenditure  of  energy  necessitated  by  such 
conditions.  As  Schuyten  has  been  wise  enough  to 
see,  this  powerful  influence  exerted  upon  perform- 


72  MENTAL   FATIGUE 

ance  by  the  manifold  forms  of  will  has  not  had  proper 
recognition  in  the  majority  of  experimental  tests  of 
fatigne  (Kraepelin^s  work  excepted). 

Naturally,  it  must  not  be  forgotten,  to  make  brief 
reference  to  the  matter,  that,  when  longer  tasks  are 
undertaken,  certain  internal  physiological  processes, 
such  as  nourishment,  digestion,  need  of  food,  affect 
efficiency,  and  that  variations  in  external  conditions, 
especially  of  temperature,  likewise  leave  some  trace 
upon  the  mental  condition.  But  the  most  important 
disturbing  factor,  aside  from  loss  of  attention  due 
to  intruding  ideas  and  distracting  stimuli,  is,  of 
course,  fatigue. 

Independent  fluctuations  of  psycho  physical  en- 
ergy. There  remains  yet  one  thing  to  which  we  may 
make  allusion,  tentatively.  E.  Schulze  {Prakt.  Schul- 
mann,  XLIV,  351,  cited  by  Burgerstein,  594)  and,  in- 
dependently of  him,  Teljatnik  (Burgerstein,  594  ft".) 
have  been  led  by  their  observations  to  consider  the 
possibility  that  our  diurnal  mental  efficiency  is 
subject  further  to  rhythmic  fluctuations  that  oc- 
cur regardless  of  whether  we  work  or  rest,  and 
that  do  not  coincide  with  the  divisions  of  our  work 
that  are  determined  by  pauses  for  the  taking  of  tood 
and  its  digestion.  Then  too,  W.  Stern  (120),  and 
after  him.  Lay  (417)  proved  what  had  long  been  as- 
sumed as  true,  that  there  is  a  movement  of  energy 
between  two  maxima  that  are  separated  by  a  mini- 
mum at  noon  and  in  the  early  afternoon.  But  smce 
this  depression  of  mental  efficiency  is  plainly  condi- 
tioned by  the  midday  meal,  it  is  not  an  independent 
and  special  factor.  Schulze  and  Teljatnik,  however, 
have  reference  to  a  phenomenon  which  appears  inde- 


RESULTS  73 

pendently,  and  wMch,  if  it  be  confirmed  by  subse- 
quent investigations,  would  add  another  new  factor 
to  the  already  sufficiently  large  number  of  them. 

What  course  a  bit  of  work  actually  takes,  i,  e., 
what  variations  in  efficiency  actually  appear  in  its 
course,  which  factors  are  most  in  evidence,  and  which 
most  determine  the  form  of  the  curve  of  work — all 
this  depends  on  the  character  of  the  work,  on  the 
peculiarities  of  its  subject-matter,  on  the  manner  of 
its  execution  and  likewise  on  the  individuality  of  the 
worker,  on  his  general  disposition  and  upon  the 
changing  external  conditions.  To  isolate  these  sev- 
eral factors,  to  bring  each  one  of  them  into  play  by 
itself  while  the  others  are  completely  suppressed,  is 
something  that  is  at  present  quite  impossible  of  ac- 
complishment. It  is,  however,  feasible,  theoretically, 
to  isolate  these  factors  in  the  large  and  to  study  their 
effects  one  by  one. 


THE   LAWS   OF  FATIGUE 

The  laws  of  fatigue,  particularly,  can  be  laid  down, 
at  least  in  a  broad  and  general  way,  thanks  to  every- 
day observation  and  to  those  experimental  investiga- 
tions of  the  last  decade  to  which  we  have  already 
given  attention. 

The  phases  of  fatigue.  These  observations  have 
shown  that  fatigue  passes  through  different  stages 
or  phases  of  development.  A  piece  of  work  that  has 
at  first  shown  improvement  in  quality  and  quantity, 
gradually  undergoes  a  change  that  we  must  ascribe 
to  fatigue.  The  fatigue  may  have  been  really  pres- 
ent for  some  time  before — though  it  is  questionable 
whether  we  should  assume  that  it  began  at  the  mo- 
ment that  the  work  began  (Cf.  Claparede's  discus 
si  on,  241  ff.) — ^but  we  notice  it  now  for  the  first  time. 
This  is  the  first  stage  of  fatigue.  During  it,  the 
speed  of  work,  it  is  to  be  noted,  continues  to  increase ; 
we  accomplish  more,  e.  g.,  more  computations  or 
more  counting,  in  each  unit  of  time ;  but  the  quality 
deteriorates;  more  mistakes  are  made.  In  the  sec- 
ond stage,  the  quantity  of  work  done  in  a  given  unit 
of  time  also  decreases.  In  the  third  stage,  with  some 
persons  the  work  becomes  slower  and  slower  and 
finally  is  given  up  entirely ;  with  other  persons  there 
is  developed  a  considerable  excitement.  Fere  calls 
this  condition  fatigue-intoxication.  We  again  do 
more  work,  but  the  work  is  hurried  and  irregular; 

74 


THE  LAWS   OF   FATIGUE  75 

our  pulse  is  rapid  and  weak ;  our  movements  are  un- 
certain; our  sensitivity  to  pain  is  augmented  (Yan- 
nod),  as  is  the  sensitivity  of  the  sense-organs.  Meu- 
mann  (II,  121),  for  instance,  has  shown  that  sensi- 
tivity for  noises  is  increased.  And  finally,  this  stage 
is  terminated,  as  we  should  expect,  by  exhaustion 
and  breakdown. 

Types  of  fatigue  or  types  of  work.  This  descrip- 
tion applies  to  the  ideal  form  of  the  development  of 
fatigue  in  the  case  of  long-continued  work.  But  the 
variations  in  efficiency  are  not  always  as  simple  as 
this,  even  in  work  of  a  constant  character,  still  less 
so  in  the  multiform  work  of  the  schoolroom. 

In  this  connection  we  may  distinguish  four  types 
of  work-curve.  The  simplest  or  falling  type  is  that 
in  which  the  application  of  the  test-work  reveals  a 
steady  decline  in  efficiency  and  a  steady  rise  in  the 
number  of  errors.  Exactly  opposite  to  this  is  the 
rising  type  in  which  the  test-work  reveals  a  progres- 
sive diminution  in  the  number  of  errors,  which  are 
fewest  in  the  last  hours  of  the  forenoon.  A  variation 
of  the  first  or  falling  type  is  the  ^convex'  type,  i.  e., 
one  in  which  the  curve  rises  a  little  at  first  (decrease 
in  errors)  and  then  shows  an  unbroken  drop  (con- 
stant increase  in  errors).  Finally,  the  fourth  or 
^concave'  type  of  curve  may  be  considered  as  a  vari- 
ant of  the  second  or  rising  type ;  in  it,  efficiency  falls 
at  first,  then  continues  to  rise  to  the  end  of  the  work, 
i.  e.,  the  errors  increase  at  first,  and  then  steadily  de- 
crease (Cf.  Blazek,  also  Kemsies,  Arheitshyg.  17  and 
Arheitstypen).  It  is  possible  to  regard  these  pecu- 
liarities in  the  general  shape  of  the  work-curve  as 
due  simply  to  individual  differences  in  type  of  fa- 


76  MENTAL   FATIGUE 

tigue ;  in  that  case,  the  curves  would  really  be  curves 
of  fatigue.  Or  we  may  regard  them  as  caused  by 
individual  differences  in  manner  of  working — differ- 
ences in  the  degree  to  which  work  incites  or  interests 
— and  these  differences  would  then  be  thought  of  as 
added  to  the  effect  of  fatigue.  In  that  case  we  have  a 
more  complicated  work-curve,  in  which  the  decisive 
element  is  the  individually  different  pure  curve  of 
work.  This  would  be  the  case  with  the  rising  and 
the  concave  type  of  curve,  whereas  with  the  falling 
and  convex  curves  fatigue  would  be  the  primary 
factor. 

It  is,  of  course,  to  be  remembered  that  these  types, 
as  we  have  described  them,  are  valid  only  for  the 
forenoon  work  of  the  school.  What  kinds  of  types 
would  be  discovered  if  we  took  into  consideration  the 
work  of  a  whole  day  is  yet  to  be  ascertained. 

F atiguability  is,  therefore,  a  thing  that  shows 
marked  differences  in  different  persons,  even  in 
healthy  persons  of  the  same  age.  It  is  worth  while 
calling  attention  to  Kraepelin's  proposal  {Arch.  /.  d. 
ges.  Psych.,  I)  that,  when  there  is  a  system  of  sec- 
tions or  parallel  classes,  the  pupils  should  be  divided, 
on  occasion  and  by  way  of  experiment,  on  the  basis 
of  their  fatiguability,  in  order  to  render  possible 
treatment  suited  to  their  special  type.  M.  Brahn  has 
argued  in  the  same  vein.  Susceptibility  to  fatigue, 
as  is  well  known,  is  greater  in  those  who  are  ill,  par- 
ticularly in  those  who  suffer  from  traumatic  neuro- 
ses. With  them  the  fatigue  is  considerably  greater 
than  that  experienced  by  the  most  easily  fatigued 
well  persons,  as  W.  Specht  {Arch.  f.  d.  ges.  Psych., 
ni)  has  demonstrated  by  the  use  of  the  method  of 


THE   LAWS   OF   FATIGUE  77 

continuous  adding.  By  this  experiment,  SpecM,  and 
later  on  Bonoff,  showed  how  we  might  detect  simu- 
lation. 

Age.  Age  is  an  important  conditioning  factor  of 
fatigue.  Every  father  who  has  taken  his  youngest 
out  for  a  stroll  knows  well  enough  that  little  children 
tire  out  extraordinarily  quickly.  Of  course,  it  is 
quite  out  of  the  question  to  carry  out  any  exact  deter- 
mination of  mental  fatigue  with  them,  because  after 
a  very  short  time  they  simply  won't  do  anything 
more,  and,  according  to  all  appearances,  before  they 
are  particularly  fatigued.  Older  children,  like  the 
six-year  olds  in  our  school,  give  plain  evidence  of 
fatigue  after  an  hour,  indeed,  often  after  half  an 
hour  of  school  work  that  includes  both  bodily  and 
mental  tasks.  These  signs  of  fatigue  appear  all  the 
sooner  if  the  children  have  not  previously  been  used 
to  continuous  activity.  It  is  not  surprising  that 
school  hygienists  (Burger stein,  Adsersen,  Hertel) 
have  been  able  to  discover  a  rise  in  the  death-rate 
during  the  first  year  of  school  life.  And  this  fact 
gives  good  warrant  for  the  plan  of  G.  Kerschen- 
steiner,  director  of  the  Munich  Voiles schule,  who 
softens  the  transition  to  the  more  severe  exactions 
of  the  school  by  a  freer  method  of  instruction  which 
leads  over  gradually  from  the  liberty  of  the  nursery 
to  the  strict  discipline  of  the  school.  However,  effi- 
ciency increases  rapidly  with  age ;  most  pupils  of  14 
and  15  and  over  show  little  trace  of  fatigue,  even 
after  three  hours  of  school  work.  Of  course,  it  is  to 
be  borne  in  mind  that  these  pupils  also  help  them- 
selves out  by  relaxing  their  attention,  and  that  class 
instruction  gives  more  chance  for  this  than  does  indi- 


78  MENTAL   FATIGUE 

vidual  instruction.  During  the  period  of  the  best 
mental  and  physical  efficiency,  namely  from  20  to  30, 
or  perhaps  to  40,  f  atiguability  is  naturally  relatively 
the  least  of  any  time  of  life.  Thereafter  it  slowly 
increases  again. 

It  would  be  a  mistake  to  suppose  that  this  decrease 
of  susceptibility  to  fatigue,  or  this  increase  of  effi- 
ciency, keeps  pace  uniformly  with  increase  of  age. 
Gilbert  found  by  the  use  of  the  tapping  test,  which, 
to  be  sure,  is  not  especially  accurate,  that  the  in- 
crease of  efficiency  with  age  is  interrupted  by  periods 
of  special  fatiguability,  more  specifically  at  8,  13-14 
and  16  years — the  years,  then,  of  more  rapid  phys- 
ical growth  (in  Claperede,  208  f.). 

Puberty.  Mental  growth,  like  bodily  growth,  is 
especially  influenced  by  puberty,  and  much  more  so 
in  girls  than  in  boys.  During  this  period,  fatigua- 
bility, to  speak  of  that  alone,  is,  as  a  rule,  distinctly 
increased.  The  school  should  then  reduce  its  scho- 
lastic requirements.*  But,  in  our  German  Gymnasia, 
the  work  of  the  Quinta,  which,  as  everyone  knows, 
makes  unusual  exactions  upon  the  pupils,  falls  in  the 
beginning  of  this  period.  Intelligent  schoolmen,  like 
Eichter  {Lehrprohen,  XV,  29)  have  for  some  time 
called  attention  to  this  evil.  Since  pubertal  develop- 
ment, on  the  average,  sets  in  with  girls  at  the  13th 
year,  but  with  boys  only  at  the  15th  year,  it  will  not 
do  to  educate  the  two  sexes  together  during  the  12th 
to  the  17th  years.    For,  from  12  to  15,  the  require- 

*H6fler  (29  f.,  39,  60  f.,  176  ff.)  has  shown  us  how  this  can  be 
done  in  the  case  of  mathematics  by  limiting  (rather  than  omitting) 
certain  definition  and  demonstration  work  as  given  in  Euclidian 
geometry,  and  how  this  more  hasty  treatment  of  the  subject  may 
be  carried  out  without  doing  any  lasting  damage  by  lack  of  thor- 
oughness. 


THE  LAWS   OF   FATIGUE  79 

ments  would  be  too  high  for  the  girls,  if  the  average 
efficiency  of  boys  of  this  age  were  taken  as  the  stand- 
ard ;  while  from  15  to  17,  they  would  perhaps  be  too 
high  for  the  boys,  if  they  were  based  upon  the  aver- 
age efficiency  of  the  girls;  or  else  the  requirements 
would  have  to  be  reduced,  at  first  in  the  interest  of 
the  girls,  in  which  case  the  boys  would  not  be  ade- 
quately stimulated;  later  on  in  the  interest  of  the 
boys,  in  which  case,  again,  the  efficiency  of  the  girls 
would  not  be  turned  completely  to  account.  This  is 
an  argument  advanced  by  Burgerstein  (524  ff.) 
against  coeducation  in  the  German  middle  schools, 
and  it  is  worthy  of  serious  consideration.  For  the 
rest,  the  relations  between  sex  and  fatiguability  are 
still  quite  as  uncertain  as  those  between  intelligence 
and  fatiguability.  The  greater  susceptibility  to 
fatigue  of  younger  children  is  to  be  met  by 
shorter  lesson-periods,  fewer  hours  of  study  and 
more  frequent  pauses,  particularly  in  the  primary 
grades. 

Length  of  lesson-periods.  In  dealing  with  the  mat- 
ter of  the  length  of  lesson-periods  we  may  as  well 
see  clearly  at  the  start  that  human  nature  gives  us  no 
absolute  warrant  whatsoever  for  making  a  lesson- 
period  exactly  an  hour,  exactly  60  minutes.  The  fact 
that  this  is  the  most  usual  length  [in  Germany]  is 
due  to  the  simple  fact  that  the  clock  is  divided  into 
12  sections;  in  other  words,  we  use  hours  in  school 
just  because  we  have  got  used  to  dividing  up  our  day 
into  twice  twelve  parts.  And  we  divide  our  day  by 
twelves  for  the  same  reason  that  we  buy  our  collars, 
our  handkerchiefs,  and  our  candles  by  the  dozen 
rather  than  by  tens,  just  because  of  a  preference  for 


80  MENTAL   FATIGUE 

the  number  twelve  that  even  the  ancient  Babylonians 
were  conscious  of.  This  preference,  or  special  fond- 
ness, for  the  number  twelve  is  to  be  traced  to  the 
astronomical  fact  that  the  moon  encircles  the  earth 
twelve  times  in  one  year.  To  take  such  a  purely  ex- 
traneously  determined  custom,  however  ancient  it 
may  be,  as  a  basis  for  the  division  of  work,  and  on 
the  basis  of  it  to  make  every  portion  of  work  the 
same  for  persons  of  every  age,  for  every  kind  of 
material,  for  every  method  of  procedure,  and  for 
every  time  of  the  day,  as  our  school  programs,  taken 
as  a  whole,  have  done  down  to  the  most  recent  times, 
is  perfectly  absurd.  The  only  rational  time  at  which 
to  stop  work  and  to  indulge  in  a  restorative  pause 
is  the  time  at  which  the  worker  feels  that  he  is  get- 
ting tired,  or  at  which,  if  he  does  not  notice  his 
fatigue  himself,  he  nevertheless  displays  easily  rec- 
ognizable signs  of  fatigue,  e.  g.,  in  addition  to  the 
poorer  quality  of  his  work  (which  is  of  special  im- 
portance in  experimental  investigation),  particularly 
signs  of  uneasiness,  decrease  of  attention,  and  a 
tendency  to  dawdle — symptoms  which  may  even  be 
seen,  not  only  in  ordinarily  attentive  and  conscien- 
tious children,  but  also  in  adults  These  and  other 
like  symptoms  should  obviously  not  be  regarded,  as 
is  all  too  often  the  case,  as  invariably  punishable 
offenses,  but  as  signals  of  fatigue,  as  signs  that  the 
work  ought  now  to  be  stopped  and  opportunity  given 
for  rest.*  To  decide  when  the  pupil  has  reached  this 
stage  in  his  work  is  precisely  the  teacher's  problem. 
To    do   it   he   needs   psychological   understanding. 

*F.  Galton,  Jouw  AntJirop.  Inst,  and  Revue  sclent.,  XVII  (1889)  ; 
also  A.  M.  Boubier,  Arch,  de  Psych.,  I  (1902). 


THE  LAWS   OF   FATIGUE  81 

Moreover,  the  teacher  can  niake  allowance,  without 
introducing  any  pause,  within  any  given  part  of  the 
school  program,  for  the  fatigue  (which,  as  we  know, 
does  not  exactly  conform  to  the  program  divisions) ; 
he  can  check  the  too  rapid  development  of  fatigue 
by  changing  his  manner  of  treating  the  subject-mat- 
ter of  the  lesson,  by  making  a  transition  to  some 
other  phase  of  the  same  subject-matter,  and  by  other 
similar  variations.  In  this  way  he  can  fit  the  length 
of  the  lesson-period  specified  in  the  school  program 
to  the  individual  needs  of  his  classes. 

On  the  other  hand,  the  length  of  the  lesson-period 
in  general  cannot,  of  course,  so  far  as  the  public 
schools  are  concerned,  be  cut  to  fit  the  special  needs 
of  a  single  class,  but  must  be  arranged  to  suit  the 
average  efficiency  of  all  the  classes  of  the  same 
grade.  It  would  need  only  a  few  well  distributed  ex- 
perimental tests  to  secure  the  information  necessary 
for  this  purpose.  It  is  only  in  the  last  15  years  that 
we  have  brought  about  what  the  investigations  of  the 
school  hygienists  have  been  demanding  for  the  past 
40  years,  that  here  and  there  authorities  have  shaken 
themselves  free  from  the  bonds  of  the  customary 
distribution  of  time  into  hours  and  have  gTanted  to 
the  younger  pupils,  or  at  least  to  the  more  easily 
fatigued  elementary  grades,  the  shorter  lesson- 
periods  which  the  maturer  pupils  of  the  higher 
schools  have  long  enjoyed.  For  feeble-minded  chil- 
dren, indeed,  a  half -hour  ought  to  be  regarded  as 
long  enough  for  a  period  (Heller). 

Thus,  in  the  middle  schools  of  Norway  {Gymnasia 
and  the  like)  the  lesson-period,  since  1896,  has  been 
limited  to  45  minutes,  and  in  Berlin,  since  1898,  the 


82  MENTAL   FATIGUE 

period  has  been  set  at  30  minutes,  at  least  for  the 
lowest  grades  of  the  Volksschule.  Like  improve- 
ments have  been  tried  in  other  cities  (Cf.  Burger- 
stein,  543  ff.).  It  is  to  be  recommended,  however, 
that,  for  the  upper  grades  of  the  Volksschule,  and 
still  more  for  the  more  exacting  Mitt  els  chute,  the 
lesson-period  be  increased  to  45-50  minutes  (the  so- 
called  'short-hour'),  and  that  a  pause  of  increasing 
length  be  introduced  after  every  period.  At  Karls- 
ruhe, since  1894,  the  limitation  of  the  class-period  to 
50  minutes  in  the  Oberrealschule  and  the  Realgym- 
nasium  has  yielded  good  results  and  has  made  it  pos- 
sible to  have  a  continuous  five-hour  session  (Treut- 
lein).  And  E.  Keller  {Intern.  Archiv.,  II,  297  tf.), 
according  to  the  unanimous  verdict  of  his  school- 
board  (which  was  at  first  distrustful  of  the  idea), 
has,  by  the  use  of  a  40-minute  period,  attained  excel- 
lent results,  especially  in  the  lower  classes,  in  the 
Realgymnasium  and  the  trade  school  at  Winterthur. 
Nevertheless,  it  will  sometimes  be  found  worth  while, 
for  the  sake  of  school  work,  to  extend  the  lesson  over 
the  hour  period.  To  this  point  we  shall  return  later 
on.  Eeducing  everything  to  rule,  however  desirable 
it  may  be,  is  more  likely  to  work  injury  in  educa- 
tional work  than  it  is  in  any  other  field.  W.  Hellpach, 
of  Karlsruhe,  proposes  as  a  regular  weekly  schedule 
the  introduction,  in  addition  to  the  ordinary  short- 
hours  of  45  minutes,  of  six  'long-hours'  of  80  min- 
utes each — this,  however,  only  for  the  upper  grades 
whose  members  have  passed  the  period  of  puberty, 
and  only  for  review  work.  But  even  this  type  of 
work,  if  the  pupils  co-operate  actively,  makes  inten- 
sive demands  upon  time,  as  may  be  noted  in  every  bit 


THE   LAWS   OF   FATIGUE  83 

of  assigned  work  or  class  work  that  lasts  more  than 
an  hour.  To  use  such  long  hours  as  a  regular  sched- 
ule would  be  a  debatable  proposition. 

Numher  of  periods  per  day  and  per  iveeU.  A  new 
question  arises  when  we  discuss  the  total  number  of 
class-exercises  per  day.  Instinctively,  and  quite  prop- 
erly, most  schools  are  inclined  to  limit  the  formal 
program  to  three  forenoon  and  two  afternoon  periods 
[hours],  and  to  allow  a  maximum  of  four,  or  at  most 
five  periods,  only  in  the  case  of  exclusively  forenoon 
sessions.  At  the  Hamburg  Gymnasium^  however,  as 
many  as  six  periods  have,  for  some  time,  been  com- 
bined into  a  single  ^morning'  session — from  9  to  3 
in  the  winter  and  from  8  to  2  in  the  summer— though, 
of  course,  in  conjunction  with  suitable  rest-pauses 
(Treutlein,  20).  And  the  same  arrangement  is  often 
followed  in  Sweden  (Burgerstein,  Handhuch,  590). 
A  similar  experiment  (six periods  of  45  minutes  each) 
was  made  at  Elberfeld  in  1899,  but  after  several 
years'  trial,  they  returned  to  a  five-period  schedule, 
because  the  higher  school  authorities,  who  could  not 
convince  themselves  of  the  advantage  of  the  plan,  for- 
bade it,  and  with  right.  Even  the  fifth  period,  despite 
longer  pauses,  is,  at  least  with  industrious  pupils,  of 
little  value.  When  the  pupils  co-operate  actively, 
four  successive  hours  of  required  work  constitute  the 
maximum.  Anyone  who,  in  his  student  days,  has  at- 
tended lectures  for  four  hours  in  succession  will  re- 
member that  he  was  unable  to  take  in  anything  more 
after  the  fourth  lecture — and  here  all  the  periods 
were  '  short  hours '  and  he  himself  was  a  grown  man. 
Kemsies'  observations  are  in  accord  with  these  state- 
ments, and  he  proposes  {Arbeit shy giene,  64)  four 


84  MENTAL  FATIGUE 

hours  for  younger  and  five  for  maturer  pupils  as  the 
maximum  per  day.  G.  Heberich  and  K.  Schmid-Mon- 
nard  (292  ff.)  demand  that  the  maximal  number  of 
hours  per  week  shall  be  24  regular  hours.  This  figure 
is  least  exceeded  by  the  humanistic  Gymnasia  of  Ba- 
varia, with  their  27  periods  in  the  highest  classes, 
as  compared  with  31  in  the  Bealgymnasium.  It  is 
another  question  how  much  time  should  be  permitted 
for  optional  work.  It  can  hardly  be  denied  that  very 
many  pupils  do  too  much  for  their  good,  and  that 
many  teachers  do  not  restrain  them  from  it,  as  if  this 
elective  work  made  no  demands  on  nervous  energy. 
For  this  type  of  work,  too,  a  maximum  time  should  be 
allotted ;  three  periods  a  week  in  science,  three  or  four 
in  music,  two  or  three  for  drawing  and  stenography 
should  be  the  maximum  for  elective  hours.  If  the 
home  throws  a  burden  of  added  hours  on  the  pupil, 
then  it  must  itself  take  the  responsibility  for  it.  But 
it  would,  however,  be  well  for  the  school  to  warn  the 
parents  over  and  over  again  of  the  dangers  of  such 
overburdening  of  their  children  and  to  show  them 
very  clearly  what  their  responsibility  is  in  this  mat- 
ter, for  they  are  seldom  sufficiently  well  aware  of  it 
(see  also  Dornberger,  Med.  Prax.,  13). 

Days  of  the  iveek.  Another  debated  question  is: 
What  days  of  the  week  are  most  favorable  for  mental 
work?  School  authorities  are  apt,  as  a  rule,  to  think 
nttle  of  the  days,  or  at  least  of  the  first  half  of  the 
days,  that  follow  Sundays  and  holidays,  and  it  is,  in- 
deed, out  of  kindly  consideration  of  this  circumstance 
that  in  many  places  it  is  forbidden  to  assign  written 
tests  or  problems  on  these  days.  Kemsies  (Arheits- 
hygiene)  reached,  however,  somewhat  different  re- 


THE   LAWS   OF   FATIGUE  85 

suits,  for  he  found  the  best  days  of  the  week  to  be  the 
first  two  after  a  hoHday,  i.  e.,  Monday  and  Tuesday, 
though  to  be  sure,  Monday  was  good  only  in  the  third 
and  fourth  periods.  It  takes,  then,  somewhat  longer 
than  usual  to  get  back  the  general  swing  that  has  been 
lost  during  the  holiday.  This  difference  of  opinion 
can  be  settled  only  by  further  and  more  extensive  in- 
vestigations. In  any  case,  efficiency  falls  off  plainly 
from  Wednesday  on.  And  most  school  progTams 
take  cognizance  of  this  fact  by  inserting  a  half -holi- 
day on  Wednesday,  though  this,  to  be  sure,  does  not 
prevent  the  evasion  of  the  purpose  of  this  half-holi- 
day  in  some  places  by  the  introduction  of  optional  in- 
struction. In  France  and  in  parts  of  Austria,  Thurs- 
day is  left  entirely  free  (in  the  celebrated  Schulpf orta 
Gymnasium,  all  of  Wednesday) ;  here  the  expectation 
is  that  the  day  will  be  devoted  to  elective  work,  not  be 
spent  in  doing  nothing. 

Pauses  in  school  work.  And  this  has  brought  us 
naturally  to  discuss  the  problem  of  pauses.  Let  us 
first  consider  the  short  pauses.  What  for  purposes 
of  instruction  is  lost  by  these  pauses  in  time  is  made 
up  in  quality.  This  is  shown  clearly  by  the  experi- 
mental tests  with  exercises  in  dictation  and  computa- 
tion that  J.  Friedrich  (Zeits.  XIII),  at  Kiilpe's  insti- 
gation, applied  to  the  pupils  of  the  fourth  class  of  a 
Wtirzburg  Volhsschule.  As  has  been  known  for  a 
long  time,  the  pause  has  a  recuperative  effect — though 
naturally  only  when  it  is  actually  used  for  rest,  for 
non-compulsory  activity  (especially  in  fresh  air),  or 
for  taking  a  moderate  amount  of  nourishment,  not 
when  it  is  taken  up  with  studying  or  with  gymnastic 
exercises  or  strenuous  games,  as  is  so  often  the  case 


86  MENTAL  FATIGUE 

in  England  (Abelson,  484).  That  this  rest-pause  is 
the  more  beneficial  and  the  more  recuperative,  the 
longer  it  lasts,  and  that  its  effect  is  the  more  notice- 
able, the  longer  the  previous  work  had  been,*  is  no 
less  certain  than  that  the  rest-pause  must  be  made  so 
much  the  longer,  the  more  fatiguing  had  been  the  pre- 
vious work,  the  more  the  psychophysical  energy  had 
been  drawn  opon.  From  this  it  follows  that — if  we 
take  no  account  of  differences  in  difficulty  of  the  vari- 
ous subjects  in  the  curriculum — the  first  pause  should 
be  the  shortest,  and  that  the  pauses  should  be  made 
longer  and  longer  in  order  to  prevent  a  too  rapid  low- 
ering of  efficiency,  e.  g.,  15  minutes  at  10  o'clock,  15 
to  20  minutes  at  11  o  'clock,  and  finally,  at  least  20  min- 
utes at  12  o'clock.  In  working  with  feeble-minded 
children,  the  pauses  must  be  made  still  longer,  since 
these  children  are  much  more  liable  to  fatigue  (Hel- 
ler). What  holds  good  for  the  way  the  shorter  pauses 
are  occupied,  holds  good  also  for  the  long  ones. 

That  gymnastic  exercises  are  really  work,  and 
therefore  out  of  place  in  rest-pauses,  will  be  brought 
out  clearly  later  on. 

The  noon  intermission  is  a  pause  of  special  signifi- 
cance. As  our  day  is  at  present  divided,  this  pause 
serves  to  secure  an  abundant  supply  of  nourishment. 
The  organism  is  so  much  concerned  in  the  subsequent 
processes  of  digestion  that  it  has  little  energy  to 
spare  for  mental  work.  The  organism  demands 
quiet.  ^^Plenus  venter  non  studet  lib  enter"  is  a  well- 
established  maxim,  and  if  it  be  not  heeded,  the  work 
is  done  less  successfully  and  with  greater  effort,  as 

*The  experimental  confirmation  of  this  and  of  similar  observa- 
tions has  been  supplied  by  G.  Heiimann  {Psychol.  Arheiten,  IV). 


THE   LAWS   OF   FATIGUE  87 

Abelson  (434)  has  clearly  shown  by  esthesiometric 
tests.  And  so  the  schools  have  been  very  properly 
forbidden  to  set  tasks  that  can  be  completed  only  by 
working  over  the  noon  hour.  The  school  cannot  pre- 
vent some  pupils  from  preparing  a  part  of  their 
afternoon  lessons  and  other  eager  pupils  from  run- 
ning over  their  assigned  work  once  more  during  re- 
cesses and  intermissions.  This  undesirable  kind  of 
work  during  the  noon  hour  can  be  entirely  avoided 
only  by  giving  up  all  informational  instruction  in  the 
afternoon.  Besides,  the  noon  intermission,  which,  as 
scheduled,  is  already  much  too  short,  and  which  is 
frequently  misused  by  being  put  to  other  mental 
work,  is  yet  further  shortened,  and  to  a  considerable 
extent,  by  external  conditions.  In  the  larger  cities  it 
is  unfortunately  impossible  for  all  of  the  pupils, 
whose  instruction,  on  account  of  elective  work,  often 
runs  to  12  o  'clock,  to  get  to  their  dinner  table  by  half- 
past  12  and  to  finish  the  digestion  of  their  dinner  and 
to  regain  sufficient  mental  freshness  by  2  o'clock, 
when  the  afternoon  work  ordinarily  begins — to  say 
nothing  of  the  fatigue  set  up  by  the  morning's  work 
that  should  be  eliminated  so  far  as  possible.  The  in- 
disposition for  mental  work  that  every  teacher,  even 
the  youngest  of  us,  notes  after  eating,  and  that  many 
persons  can  drive  away  only  by  the  use  of  coffee,  is 
felt  by  the  pupil,  too,  especially  during  periods  of 
rapid  growth  and  also  when  the  weather  is  hot.  And 
the  ability  of  the  school  child  to  do  mental  work  is 
fully  restored  at  the  beginning  of  the  afternoon  ses- 
sion only  in  the  rarest  cases  (Griesbach,  Vannod, 
Wagner,  Friedrich,  and  Burgerstein  in  his  Hand- 
huch,  581  if .) .    It  is,  accordingly,  one  of  the  most  jus- 


88  MENTAL  FATIGUE 

tifiable  demands  of  school  hygiene  that  the  afternoon 
session,  if  it  be  not  done  away  with  entirely,  shonld 
begin  at  the  very  least  two  hours  after  the  noon  meal, 
i,  e.,  at  3  o'clock,  and  not  at  2  o'clock,  which  would  be 
justifiable  at  most  only  if  all  the  pupils  sat  down  to 
their  dinner  at  12  o  'clock — a  custom  that  is  becoming 
less  and  less  common  in  our  larger  cities  as  the  years 
go  by.* 

The  pause  that  yields  most  abundant  recuperation 
is,  of  course,  sleep,  during  which,  if  it  be  quiet  and 
dreamless,  it  may  be  assumed,  no  fatigue-substances 
are  produced  at  all,  while  assimilation  far  preponder- 
ates over  dissimilation.  Without  recounting  in  detail 
the  laws  of  sleep  discovered  by  Eomer,  we  may  point 
out  simply  that,  in  general,  the  same  laws  that  hold 
for  pauses  of  all  kinds  hold  also  for  sleep.  Sleep 
must,  accordingly,  be  the  longer,  the  more  strenuous 
has  been  the  work  that  has  preceded  it,  and  the  more 
easily  fatigued  the  organism  is.  It  follows  that  the 
need  of  sleep  is  the  greater,  the  farther  the  person  is 
from  the  stage  of  mental  and  physical  maturity. 
Babies  spend,  or  should  spend,  the  greater  part  of  the 
time  in  sleep.  And  Axel  Key  (166  ff.),  the  Swedish 
school  hygienist,  is  right  when  he  demands  11  hours 
of  sleep  for  7  to  9  years  old  children,  10  hours  for  10 
to  13  year  old  children,  and  as  many  as  9  hours  for 
older  pupils.  Adult  mental  workers  need  from  7  to  8 
hours.  It  must  not  be  forgotten  in  this  connection 
that  the  need  of  sleep  is  less  in  summer  than  in  win- 
ter. Unfortunately,  we  know  full  well  that  very  many 
school  children  tend  to  spend  in  sleep  fewer  hours 

♦The  Max-Oymnasiuw  at  Munich  begins  afternoon  instruction  in 
summer  anyway  as  late  as  3  o'clock. 


THE   LAWS   OF   FATIGUE  89 

than  they  should.*  The  blame  attaches  sometimes  to 
the  home,  sometimes  to  the  school,  and  frequently  the 
trouble  lies  in  external  conditions,  such  as  poverty 
and  the  like,  over  which  neither  school  nor  home  has 
control  (Cf.  Burger  stein,  680  f.)  The  recuperative 
effect  of  sleep  is,  of  course,  the  greater,  the  less  the 
organism's  activity  is  continued  in  it,  the  less,  in 
other  words,  the  sleep  is  disturbed — ^whether  by  out- 
ward impressions,  by  dreams,  by  the  after-effects  of 
strenuous  mental  work  undertaken  just  before  going 
to  bed,  or  finally,  by  indigestible  or  stimulating  sup- 
pers. It  is,  therefore,  essential  that  pupils  should  not 
be  allowed  to  continue  their  study  up  to  the  time  they 
go  to  bed,  but  should  be  busied  with  light  reading, 
simple  music  or  games  and  the  like.  All  the  school 
can  do  in  this  connection  is,  of  course,  to  give  good 
advice  to  the  parents.  The  school  has  still  more  in- 
terest in — but,  unfortunately,  has  still  less  influence 
upon — the  external  conditions  under  which  children 
get  their  sleep — conditions  which,  as  Friedrich  has 
shown  for  Wlirzburg,  Bernhard  for  Berlin,  and  Ra- 
venhill  for  English  elementary  schools,  are  often  the 
worst  conceivable.  If  a  full  amount  of  sleep  is  not 
sufficient  to  restore  the  capacity  for  work  completely 
by  the  next  morning,  then  the  demands  made  on  the 
organism  by  the  work  of  the  previous  day  were  too 
great  for  its  efficiency.  This  might  occur  either  be- 
cause the  efficiency  had  itself  been  weakened  (per- 
haps by  illness  or  inadequate  nutrition),  or  because 
excessive  demands  had  been  made  upon  a  person  of 
perfectly  normal  efficiency,  i.  e.,  upon  an  efficiency 

*D6rnberger  and  Grassmann   (12)   found,  however,  that  pupils 
in  the  Oymnasia  at  Munich  had  enough  sleep. 


90  MENTAL  FATIGUE 

that  had  not  been  reduced  by  any  otherwise  unfavor- 
able circumstances.  In  the  first  instance,  we  have 
over- fatigue  as  a  result  of  an  abnormal  and  especially 
pathological  f  atiguability ;  in  the  second  case,  we  have 
over-fatigue  as  over-burdening,  i.  e.,  as  a  result  of 
activity  that  exceeded  the  normal  capacity.  It  is 
hard  to  prevent  occasional  over-fatigue,  and  we  need 
not  take  that  very  tragically.  But  if  it  is  repeated, 
or  if  it  persists,  and  if,  for  weeks  at  a  time,  sleep  and 
the  other  rest-pauses  that  interrupt  the  work  do  not 
completely  restore  the  efficiency  available  at  the  be- 
ginning of  the  periods  of  work,  if  the  periods  of  men- 
tal freshness  become  shorter  and  shorter,  and  if  fa- 
tigue sets  in  earlier  and  earlier — as  both  teachers  and 
pupils  frequently  experience  after  a  hard  year  of 
school  work,  or  as  mental  workers  in  general  experi- 
ence in  the  form  of  the  well-known  *  yearns  fatigue^ — 
then,  indeed,  we  have  a  condition  that  calls  for  seri- 
ous consideration.  These  symptoms  show  that,  just 
in  these  longer  periods  of  work,  the  consumption  of 
nervous  energy  has  gone  so  far  that  the  ordinary 
rest-pauses  no  longer  suffice  to  restore  it  completely. 
Quite  often,  even  in  a  case  like  this,  a  still  longer 
pause,  one  of  several  days  or  weeks,  especially  a 
vacation,  may  bring  energy  back  to  the  height  at 
which  it  usually  stands  in  the  first  weeks  of  the  school 
year.  If  the  restoration  of  the  original  efficiency  is 
not  brought  about  even  then,  we  have  undoubtedly  to 
do  with  exhaustion.  Schuyten  {Overlading,  etc.), 
unfortunately,  did  not  apply  this  final  and  decisive 
test. 

If  this  sign  of  over-fatigue,  or  exhaustion,  appears 
in  the  majority  of  its  pupils,  the  school  must  make  a 
considerable  reduction  in  its  demands  and  change  its 


THE   LAWS   OF   FATIGUE  91 

methods.  If,  on  the  contrary,  it  appears  in  only  a 
few  pupils,  the  home  must  realize  the  fact  that  the 
task  has  become  too  hard  for  the  pupil,  and  must  per- 
mit him  to  repeat  the  grade  in  order  to  give  his  body 
and  mind  a  chance  to  develop  the  physical  efficiency 
and  the  mental  maturity  that  is  absolutely  necessary. 
Or,  if  even  the  longer  rest-pauses  of  the  vacations  do 
not  restore  his  old-time  vigor,  there  may  be  some  dis- 
ease or  the  after-effect  of  an  excessive  degree  of  ex- 
haustion. To  hold  a  pupil  thus  afflicted  down  to  men- 
tal work  is  as  great  a  crime  as  to  load  him  with  over- 
Work  to  the  same  degree.  Sleep,  therefore,  affords 
us  a  reliable  criterion  for  the  differentiation  of  nor- 
mal fatigue  from  that  which  is  induced  by  patho- 
logical or  other  unfavorable  conditions  or  by  over- 
burdening. 

There  is  better  agreement  as  to  the  significance  of 
sleep  than  as  to  the  most  advantageous  length  and 
distribution  of  the  longer  pauses  in  school  work,  i,  e., 
the  vacations.  In  southern  Germany  the  usual  ar- 
rangement calls  for  nine  weeks  of  vacation  in  the 
summer,  10  days  at  Christmas  and  16  days  at  Easter, 
with  no  long  vacation  at  Pentecost,  but  in  northern 
Germany  there  is  a  vacation  at  Pentecost,  and  the 
somewhat  shorter  summer  vacation  is  divided  into 
two  parts,  though,  it  must  be  admitted,  not  without 
much  opposition.  The  Christmas  and  Easter  vaca- 
tions are  here  approximately  as  long  as  in  southern 
Germany.* 

Again,  many  observers  feel  sure  that  relatively 


♦Burgerstein  points  out  that  hygienic  considerations  other  than 
fatigue  favor  a  threefold  division  (Die  zweckmdssigste  Regelung 
d.  Ferienordnung,  In  Bericht  u.  d.  I4  Intern.  Kong.  f.  Hygiene  u. 
DemograpJiie,  Berlin,  1907,  Vol.  II). 


92  MENTAL  FATIGUE 

short  and  frequent  vacations  are  more  favorable  for 
school  work  than  relatively  longer  and  fewer  ones. 
Certain  it  is  that,  during  long  vacations  of  several 
weeks  duration,  the  pupils  drift  farther  away  from 
the  spirit  of  school  work  than  they  do  during  short 
intermissions  of  only  one  or  two  weeks.  Yet  this  is  no 
disadvantage  from  the  hygienic  point  of  view.  It  is 
a  good  thing  for  pupils  completely  to  forget  their 
school  cares  and  duties  once  in  a  while,  and  this  they 
can  scarcely  do  in  one  or  two  weeks.  Of  course,  it  is 
equally  true  that  they  forget  a  good  deal  of  what  they 
ha^e  learned  as  well.  But  systematic  drill,  with  repe- 
tition, can  re-create  this  lost  material  in  the  first 
weeks  of  the  new  term,  without  delaying  entrance 
upon  the  new  work  for  which  the  pupils  are  eager. 
However,  this  is  a  matter  that  has  not  been  suffi- 
ciently tested  scientifically  as  yet. 

Even  if  the  loss  occasioned  by  the  long  vacation 
could  not  be  easily  recovered,  nevertheless  the  ar- 
rangements of  vacation  periods  already  made  by  the 
school  authorities  and  in  other  social  and  business 
circles  would  have  to  be  considered.  To  make  new 
vacation  arrangements  at  the  risk  of  rendering  more 
difficult  the  gathering  together  of  the  whole  family  (a 
custom  that  leads  to  the  arousal  of  a  multitude  of 
stimulating  ideas  in  the  new  surroundings  of  country 
life  and  that  affords  both  children  and  parents  oppor- 
tunity for  a  more  intimate  mental  intercourse  than 
the  busy  days  of  the  remainder  of  the  year)  would  be 
to  administer  a  serious  setback  to  the  development  of 
family  life  that  already  suffers  manifold  restrictions 
in  other  ways.  In  this  matter  school  hygiene  will 
have  to  give  way  somewhat  to  social  and  ethical  con- 


THE  LAWS  OP  FATIGUE  93 

siderations,  to  the  hygiene  of  the  spirit  of  family 
life,  and  this  it  can  do  without  undue  anxiety,  since, 
so  far  at  least,  no  serious  hygienic  disadvantages 
have  been  shown  to  follow  the  long  vacation. 

The  shorter  pauses,  too,  have  their  disadvantages. 
They  break  up  the  work,  and  this  interruption  means 
loss  of  swing,  of  fitness  for  work,  or  of  the  pupiPs 
adjustment  for  the  particular  work  on  which  he  is 
engaged ;  and  if  the  interruption  is  longer,  this  means 
the  loss  as  well  of  the  readiness  for  mental  work  of 
any  kind,  the  loss,  in  other  words,  of  what  we  have 
termed  ^  general  swing. '  The  experiments  of  W.  H. 
Elvers  and  Kraepelin  {Psych.  Arheiten,  I),  of  E. 
Lindley  {Psych.  ArheUen,  III),  and  of  Heiimann 
{Psych.  Arheiten,  IV)  teach  us  that  the  loss  is  the 
greater,  the  longer  the  interruption  lasts  and  the 
more  our  attention  was  adapted  to  these  objects,  was 
accommodated  for  the  one  particular  work. 

It  is  clear  that  the  loss  of  special  fitness  is  not  in- 
jurious, provided  the  new  lesson  deals  with  a  totally 
different  kind  of  material,  but  that  it  is  very  disad- 
vantageous if  the  same  lesson  is  continued  or  if  the 
new  lesson  is  closely  related  with  the  subject-matter 
of  the  preceding  one,  i.  e.,  if  it  is  pedagogically  allied 
to  it — as,  for  example,  if  the  material  of  a  lesson  in 
history  was  to  be  worked  over  for  a  bit  of  composi- 
tion work  in  the  German  lesson  that  followed  it. 
Since,  in  a  case  like  this,  the  ideas  that  had  been 
gained  in  the  first  lesson  would  have  to  be  developed 
again  in  the  next  one,  it  is  better  to  make  the  transi- 
tion without  any  pause,  as  is,  in  fact,  usually  done  in 
the  case  of  German  composition  work.  It  is  assumed, 
however,  that  lessons  thus  prolonged  are  followed  by 


94  MENTAL  FATIGUE 

longer  pauses  for  recuperation,  and  tliat  they  should 
be  limited  in  use  to  the  upper  grades.  In  these  upper 
grades,  where,  for  the  sake  of  pedagogic  unity,  a  les- 
son must  often  present  and  work  over  a  considerable 
number  of  ideas,  the  lesson-period  in  general  must 
frequently  be  longer  than  in  the  lower  grades.  And 
the  lessened  susceptibility  to  fatigue  of  these  maturer 
pupils  makes  such  an  arrangement  permissible. 

Naturally,  the  loss  of  general  swing  is  another  mat- 
ter. To  lose  it  works  injury  even  when  the  subject- 
matter  of  the  new  lesson  is  quite  different.  The  first 
five  or  ten  minutes  will  always  be  handicapped  by  the 
very  unfavorable  influence  of  an  incomplete  fitness 
for  work.  The  school  would  best  be  served  by  short 
pauses  which  would  permit  the  general  swing  to  bo 
maintained,  though  specific  fitness  would  be  lost,  and 
at  the  same  time  a  certain  amount  of  recuperation 
would  take  place.  To  select  just  the  best  length  for 
pauses — a  length  such  that  the  loss  of  swing  and  the 
gain  in  recuperation  would  balance  one  another — is, 
on  account  of  the  many  contributory  factors,  a  prob- 
lem by  itself,  the  solution  of  which  still  presents  so 
many  difficulties  to  experimental  psychology  that  it 
would  be  safer  and  better  for  the  school  to  choose  the 
lesser  evil,  the  loss  of  swing,  so  that  it  may  at  least 
avoid  the  greater  evil,  overburdening. 

Change  of  worlc:  special  and  general  fatigue. 
Change  of  work  also  brings  about  recuperation  often- 
times. If  we  mean  by  this  statement  that,  when  we 
resume  a  task  that  we  have  interrupted  by  some  other 
form  of  activity,  we  then  work  considerably  better 
than  before  the  interruption — that,  to  speak  more  ac- 
curately, we  enter  upon  the  task  again  with  a  fresh 


THE  LAWS   OF   FATIGUE  95 

supply  of  energy — then  the  statement,  in  view  of  the 
preceding  discussion,  is  very  much  to  be  doubted.  It 
cannot  be  supposed  that,  in  our  complicated  psycho- 
physical organism,  an  activity  of  appreciable  inten- 
sity can  run  its  course  in  any  part  of  our  complicated 
psychophysical  organism  without  thereby  affecting 
the  functions  of  the  other  portions  of  the  organism, 
and  hence  of  the  whole  organism.  And  the  more  man- 
ifold, the  more  intimate  the  connection  of  the  one  part 
with  the  remaining  parts,  the  more  rapidly  and  the 
more  extensively  will  the  fatigue  make  itself  evident 
in  these  parts  as  well. 

Conversely,  the  less  the  active  part  be  connected 
with  the  remainder  of  the  organism,  the  more  it  is 
possible  to  limit  its  functioning  to  itself,  the  more 
slowly  will  the  fatigue  spread  to  the  other  parts,  and 
the  more  possible  will  it  be  for  the  fatigue  to  take  on 
the  semblance  of  localized  and  isolated  fatigue.  This 
is  shown  by  Urbantschitsch's  observation  that  a  con- 
tinuous tuning-fork  tone  after  a  time  becomes  inaud- 
ible, although  the  striking  of  any  other  fork  readily 
evokes  its  proper  auditory  sensation.  The  organ, 
then, — ^whether  as  a  whole  or  in  some  definite  part  we 
need  not  try  to  decide — fatigues  for  just  that  one 
tone,  but  not — or  more  exactly,  not  yet — for  the 
others.  This  is  substantially  the  same  thing  as  J.  J. 
Mtiller  discovered,  when  he  proved  that  overtones  be- 
come ineffective  if  they  have  been  given  intensely 
just  beforehand.  Another  example  of  fatigue  by 
and  for  a  very  specific  activity  is  the  negative  after- 
image, for  this — at  least  in  terms  of  the  Young-Helm- 
holtz  theory  of  color  sensations — is  an  instance  of 
fatigue  for  the  color  previously  seen  (or  the  light- 


96  MENTAL   FATIGUE 

waves  that  correspond  to  tMs  color),  coupled  with 
continued  sensitivity  for  other  colors  (or  other  light- 
waves).* Finally,  the  marked  unreliability  of  the 
physiological  methods  of  measuring  fatigue,  especi- 
ally in  the  case  of  mild  degrees  of  the  fatigue  set  up 
by  mental  work,  is  most  easily  explained  by  the  as- 
sumption that  the  active  parts  of  the  organism  fa- 
tigue first  of  all,  and  that  the  organism  as  a  whole, 
especially  the  musculature,  is  only  gradually  sympa- 
thetically affected.  The  same  assumption,  too,  en- 
ables us  to  see  how  there  may  be  a  general,  as  well  as 
a  special  fitness  for  work.  There  is,  then,  such  a  thing 
as  special  fatigue,  which  we  must  look  upon  as  a 
consumption  of  the  constitutive  materials  of  the  act- 
ive organ — a  process  that  in  the  very  nature  of  the 
case  is  limited  to  the  organ  in  question — and  as  a 
secretion  of  fatigue-substances  that  accumulate  at 
first  at  the  point  where  the  work  is  done. 

Nevertheless,  there  is  no  isolated  fatigue.  The  fa- 
tigue-substances do  not  remain  where  they  are  se- 
creted, but  are  carried  forth  through  the  whole  body 
by  the  ceaseless  circulation  of  the  blood.  Thus,  there 
appears  a  general  as  well  as  a  special  fatigue.  More- 
over, the  fact  that  the  part  of  the  body  that  is  vigor- 
ously at  work  is  continuously  and  extensively  draw- 
ing recuperative  materials  from  the  circulation  must 
bring  it  about  that  a  lesser  amount  of  these  materials 
remain  at  the  disposal  of  the  other  organs.  And 
Mosso  even  believes  that  an  organ  draws  upon  the 
supplies  of  other  organs  as  well,  that  it  uses  up  their 
reserves,  so  to  speak,  e.  g.,  that  the  brain,  during  its 
activity,  draws  upon  the  muscles  for  recuperative 

*Cf.  L.  Hermann,  Lehrhuch  der  Physiologie,  26.  ed.,  523  f. 


THE   LAWS   OF  rATIGTJE  97 

substances.  TMs  is  the  second  way  in  wMch  fatigue 
may  spread  from  the  active  organ.  It  follows  quite 
clearly  from  this  that,  when  one  organ  is  intensely 
active,  there  cannot  well  be  any  storage  of  recupera- 
tive materials  in  the  other  organs,  but  that,  on  the 
contrary,  these  organs  must  also  in  time  be  exhausted. 
And,  of  course,  the  same  thing  is  true  if  vigorous 
activity  is  discontinued  in  one  organ,  but  set  up  in 
some  other  with  equal  intensity.  Accordingly,  change 
of  work,  or  more  properly,  changing  the  organ  that 
works,  does  not  bring  about  recuperation  as  long  as 
the  consumption  of  materials  continues  at  the  same 
rate. 

If,  however,  the  work  to  which  we  change  is  con- 
siderably easier — if  it  is  of  such  a  kind  that,  to  put  it 
in  the  terms  of  our  discussion,  it  generates  a  smaller 
amount  of  fatigue-substances  and  makes  smaller  de- 
mands on  the  available  supply  of  material,  and  if  the 
supply  of  material,  at  least  by  respiration,  goes  on 
unchecked — then  change  of  work  may,  it  must  be  ad- 
mitted, bring  about  recuperation.  Whether  and  to 
what  extent  a  given  piece  of  work  is  easier  depends, 
naturally,  on  the  kind  of  work  that  it  is.,  and  also  upon 
the  individuality  of  the  worker,  his  knowledge,  his 
native  abihty,  his  susceptibility  to  practice,  his  skill, 
his  interests,  and  the  like — in  short,  on  the  manner 
and  method  in  which  he  takes  his  work, 

But  we  think,  too,  that  we  can  often  discern  a  recu- 
perative effect  when  we  change  from  one  form  of  ac- 
tivity to  another  of  equal  intensity.  Here,  however, 
it  does  not  appear  that  we  are  dealing  with  recupera- 
tion in  the  strict  sense  of  the  term.  The  work  that  is 
resumed  is  not  essentially  better  than  it  was  before 


98  MENTAL  FATIGUE 

the  interruption.  Not  essentially  better,  we  must 
say,  for  the  ine^dtable  slight  pauses  do  actually  exert 
some  slight  recuperative  effect,  and  our  fresh  start  is 
affected  favorably  by  an  initial  spurt,  here  the  spurt 
of  change,  as  we  have  termed  it.  Our  work,  however, 
is  certainly  much  better  than  it  would  have  been  had 
we  continued  without  any  interruption  to  the  same 
moment  of  time.  It  is,  then,  not  really  bettered,  but 
has  simjDly  not  grown  any  worse.  Obviously,  because 
the  consumption  of  material  in  the  organ  in  question 
ceased  during  the  interruption,  whereas  in  the  second 
case,  it  would  have  continued  uninterruptedly. 

The  experiments  conducted  by  Weygandt  {Psychol. 
Arbeit  en,  II  and  Kraepelin,  Vh  erhiir  dung  sf  rage,  9 
ff.),  that  are  often  cited  as  decisive  against  the  recu- 
perative effect  of  a  change,  do  not,  of  course,  really 
suffice  to  refute  this  assumption  or  that  of  the  exist- 
ence of  partial  fatigue.  His  experiments  merely 
prove  that  if  an  easy  piece  of  work  interrupts  a  more 
difficult  one,  the  result  is  that  we  do  better  when  we 
resume  the  difficult  work  than  we  would  have  done  if 
we  had  worked  on  with  the  difficult  task  for  the  same 
length  of  time  without  the  interruption — a  result 
that  is  perfectly  intelligible  for  us  from  what  we  have 
already  seen.  His  results  do  not,  however,  prove  any- 
thing against  the  idea  of  special  fatigue  or  anything 
against  that  of  an  advantageous  effect  arising  from 
the  change  in  kind  of  work  (neither  do  the  experi- 
ments of  Schulze,  in  which  changes  were  arranged 
between  adding  and  copying  letters),  for  the  forms 
of  work  used  for  the  shifts  of  activity  (adding,  memo- 
rizing of  series  of  numbers  and  syllables,  cancella- 
tion, the  reading  of  texts  in  a  foreign  language,  etc.) 


THE   LAWS   OF   FATIGUE  99 

are  too  mucli  alike.  Of  course,  tliey  are  different 
sorts  of  operations,  but  they  involve  either  the  same 
or  similar  elements.  Physiologically  considered, 
they  are  processes  that  run  their  course  very  largely 
in  the  same  brain  regions.  Different  brain  regions 
will  always  be  brought  into  action  in  some  measure, 
if  the  subject-matter  of  a  lesson  is  treated  in  quite 
different  ways — if,  for  instance,  the  subject  is  pre- 
sented at  first  pictorially  and  concretely,  then  de- 
scriptively and  more  abstractly.  By  such  a  method 
the  pupiPs  efficiency  can  be  put  to  use  more  ration- 
ally. The  points  at  dispute  hinge  on  such  questions 
as  whether  a  specific  region  of  the  brain  can  fatigue 
without  affecting  other  regions  also;  whether  an 
activity  that  we  think  of  as  exclusively — or,  since  this 
is  hardly  conceivable,  as  predominantly — centered  in 
a  specific  part  of  the  brain,  and  that  we  must  con- 
sider as  being  predominantly  an  activity  of  a  single 
or  of  certain  determinate  phases  of  mental  life,  fa- 
tigues quite  by  itself  and  leaves  our  mind  in  full  effi- 
ciency for  such  other  activities  as  we  ascribe  to  other 
regions  of  the  brain  and  as  are  evidently  other  phases 
of  mental  life ;  whether,  then,  a  fatigue  can  not  only 
be  special  when  it  begins,  but  can  remain  special, 
isolated,  and  localized,  or  whether  it  spreads  gradu- 
ally over  the  entire  psychophysical  organism,  or 
whether,  finally,  it  induces  from  the  very  beginning 
an  equal  amount  of  impairment  of  efficiency  in  all 
parts  of  the  organism.  Our  discussions  have  shown 
that  we  must  admit  a  special  fatigue,  hut  deny  its  iso- 
lation. But  it  follows  from  this  that  change  of  work 
brings  about  for  the  regions  of  the  brain  freed  from 
work  a  cessation  in  the  consumption  of  the  materials 


100  MENTAL   FATIGUE 

of  which  the  nerve  cells  are  built  up,  so  that,  when  the 
former  activity  is  resumed,  this  fact,  taken  together 
with  the  spurt  of  change,  results  in  better  perform- 
ances than  before  the  interruption  of  the  activity, 
and  in  this  way  there  seems  to  be  a  recuperation. 

And  the  fact  that  in  the  new  work,  i.  e.,  in  what 
might  be  called  the  'change-work,'  more  is  accom- 
plished than  at  the  end  of  the  previous  work,  despite 
the  general  reduction  of  efficiency  to  be  expected  from 
the  distribution  of  the  fatigue-substances,  is  intel- 
ligible. On  the  one  hand,  the  stimulus  of  novelty  re- 
awakens interest  and  incites  us  to  a  greater  expendi- 
ture of  energy  (the  effect  of  mood).  On  the  other 
hand,  the  parts  of  the  organism  that  are  set  into  ac- 
tivity by  the  new  work  have  not  yet  been  concerned  in 
work ;  their  store  of  energy  has  not  yet  been  assailed. 

It  is,  of  course,  presupposed  that  the  previous  work 
had  fatigued  the  organism  only  moderately,  and  that 
the  new  work  is  essentially  different  from  that  that 
had  preceded  it.*  On  this  account,  the  form  of  change 
that  most  effectually  slows  the  progress  of  fatigue, 
though  it  does  not,  of  course,  entirely  check  it,  is  the 
change  from  mental  and  bodily  work.  All  in  all,  the 
view  frequently  held  by  educators  (e.  g.,  Eichter, 
Lehrprohen,  XLV,  14)  that  change  means  recupera- 
tion appears  to  be  but  the  psychologically  and  physi- 
ologically unjustifiable  interpretation  of  observations 
that  of  themselves  are  not  incorrect. 

Social  activities.    "What  we  have  said  about  the  ef- 


*  Special  (partial)  and  general  fatigue  are  distinguished  also  by 
Mosso  (244),  Kraepelin  {Uherl)urdungsfrage,  16)  and,  apparently, 
by  Claparede  (236,  but  see  218  ff.  and  268  f.),  only  that  these 
writers  lay  more  emphasis  upon  the  general  effect,  while  Teljatnik 
(in  Burgerstein,  467)  emphasizes  rather  the  partial  fatigue  effect 


THE  LAWS   OF   FATIGUE  101 

feet  of  change  of  work  holds  true  in  the  main  for  the 
effect  of  social  life.  If  the  pupiPs  social  activities 
make  only  slight  demands  on  his  mental  life,  if  they 
call  forth  only  a  moderate  degree  of  interest,  if  they 
serve  to  divert  and  amuse  rather  than  to  excite,  then 
they  are  good  things  to  conclude  the  day's  work  with, 
particularly  because  they  prevent  the  carrying  over 
(perseveration)  of  the  thoughts  and  worries  of  the 
day.*  But  if  these  social  activities  fetter  our  atten- 
tion and  render  us  ^all  stirred  up,'  then  they  are 
really  another  kind  of  work — quite  apart  from  cut- 
ting short  our  time  for  sleep — and  then  we  must  ask 
ourselves  seriously  the  question  whether  the  satis- 
faction that  we  hope  to  gain  from  them  is  enough  to 
compensate  for  the  loss  of  mental  efficiency  on  the 
following  day. 

The  home  will  see  to  it  that  school  children  at  least 
are  kept  from  strenuous  social  activities,  if  it  is  all 
desirous  that  their  studying  shall  not  be  interfered 
with. 

Gymnastics.  The  same  general  principles  apply  to 
every  sort  of  bodily  movement,  and  especially  to  g^nn- 
nastics  and  active  games.  When  these  are  pursued 
vigorously,  they  are  distinctly  fatiguing,  and  are,  in 
any  event,  not  recuperative,  as  used  to  be  generally 
beheved.  Anybody  who  has  done  intensive  gymnas- 
tic work  or  played  tennis  or  enjoyed  sport  on  the  ice 
knows  how  little  inclined  he  was  afterward  for  mental 
work.  Grriesbach,  Wagner  and  Vannod  found  a  con- 
siderable reduction  in  the  sensitivity  of  the  skin 
under  such  conditions.    And  other  investigators  have 

*0n  perseveration,  see  Offner,  Das  Geddchtnis,  23  f.  and  else- 
where. 


102  MENTAL   FATIGUE 

in  other  ways  proved  that  gymnastics  exert  a  strong 
fatigue-effect;  in  fact,  all  who  have  used  scientific 
methods  of  measurement  have  come  to  striking 
agreement  on  this  point  (Cf.  Burger  stein,  570  ff.)-* 
However,  this  kind  of  fatigue-effect,  when  of  moder- 
ate degree,  has  the  merit  that  one  speedily  recovers 
from  it,  so  that,  even  after  an  hour's  rest,  especially 
if  nourishment  be  taken  during  that  time,  one  feels 
again  prepared  for  mental  work  and  one  may  ac- 
complish very  good  results  in  it  (Cf.  Abelson,  414, 
486).  The  reason  for  this  is  that  there  are  operative 
here  other  favorable  factors  which  can  soon  cancel 
the  fatigue-effect.  The  vigorous  exercise,  especially 
when  taken  in  fresh  air,  the  augmented  metabolism 
and  the  consequent  augmented  supply  of  the  mate- 
rials that  build  up  the  body,  particularly  the  aug- 
mented supply  of  oxygen  through  the  quickening  and 
deepening  of  respiration  and  of  nutritive  material 
through  the  quickening  of  appetite,  the  hastening  of 
the  elimination  or  the  oxidization  of  the  fatigue- 
13roducts,  all  these  are  factors  that  condition  a  rapid 
renewal  of  the  stock  of  psychophysical  energy  used 
up  by  the  strenuous  bodily  activity.  So  that  gymnas- 
tics may,  after  all,  possess  indirectly  an  unquestioned 
recuperative  value,  not  merely  an  apparent  one,  as 
Gaupp  (118)  thinks.  When  interpreted  in  this  way, 
there  is  justification  for  the  general  opinion  of  the 
value  of  exercise — an  opinion  in  which  no  distinction 
is  made  between  the  direct  and  the  indirect  effect  of 
exercise.    If,  however,  the  subsidiary  effects  which 

*See  also  the  results  of  Smedley  at  Chicago,  in  Rept  Dept.  Child- 
Study  and  Pedagogic  Investigation  (46th  An.  Rept  Brd.  Educ, 
Chicago),  1899-1900.— Translator. 


THE  LAWS   OF   FATIGUE  103 

bring  about  this  rapid  compensation  of  the  fatigue 
were  to  be  restricted,  then  the  fatigue-effect  of  bodily- 
exercise  would  assume  large  proportions.  Thus, 
gymnastics  in  closed  or  poorly  ventilated  rooms  have 
very  little  value.  Since  these  beneficial  secondary 
factors  are  not  immediately  effective,  it  is  easy  to 
understand  why  we  are  not  in  a  position  to  do  inten- 
sive mental  work  directly  after  active  physical  exer- 
cise, but  only  after  a  rest  of  three-quarters  of  an 
hour  or  an  hour.  In  cases,  however,  like  that  cited  by 
Holmes  (Ped.  Seminary,  III),  who  found,  by  means 
of  the  addition  test  and  a  test  of  bisection  of  lines, 
that  a  moderate  walk  and  a  brief  four-minute  calis- 
thenic  exercise  in  the  school  room  were  directly  stim- 
ulating to  mental  work,  and  like  that  cited  by  Dorn- 
bltith,  who  noted  a  similar  result  after  a  gymnastic 
lesson  that  did  not  make  great  demand  on  energy  or 
attention — in  these  cases,  we  must  conclude  that  the 
consumption  of  energy  by  the  physical  activity  is 
more  than  compensated  by  those  indirect  effects  that 
augment  the  supply  of  energy.  Moreover,  in  the  case 
of  walking,  rhythm  is  a  factor  that  is  not  to  be  under- 
estimated, since  it  exerts  a  favorable  influence  upon 
our  mood  (Cf.  Otfner,  Bas  Geddchtnis,  84,  86,  190). 
That  a  short  walk  might  have  a  stimulating  effect  we 
showed  previously,  in  our  discussion  of  swing.  There 
are,  then,  considerable  differences  in  the  effect  on 
mental  efficiency  of  different  kinds  and  degrees  of 
bodily  movement,  and  variations  in  the  bodily  consti- 
tution of  the  individual  introduce  yet  other  differ- 
ences. 

Science  can  only  lay  down  general  principles.    It 
will  be  the  business  of  the  home  and  of  the  school  to 


104  MENTAL  FATIGUE 

determine  for  particular  children,  or  groups  of  chil- 
dren, by  dint  of  careful  observation,  in  what  way,  to 
what  degree,  and  at  what  time  physical  activity  is  a 
healthy  counteractivity  for  mental  work :  as  it  will  be 
also  their  business  to  determine  how  gymnastics,  that 
obviously  serve  not  only  hygienic,  but  also  pedagog- 
ical purposes  (training  in  discipline,  order,  vigor  and 
physical  development),  shall  be  given  due  place  along 
with  the  studies  of  the  school,  and  how  neither  physi- 
cal nor  mental  training  shall  suffer  from  the  other, 
but  shall  be  of  mutual  advantage.  The  working  out 
of  this  problem  is  the  art  of  pedagogic  diplomacy. 
Theory  can  supply  only  certain  guiding  principles, 
the  most  important  of  which  are :  Physical  activity  is 
also  fatiguing  work.  It  cannot,  therefore,  afford  re- 
cuperation after  mental  work,  but  itself  demands  a 
period  of  rest.  It  is,  however,  accompanied  by  sec- 
ondary results  that  are  extremely  helpful  for  recu- 
peration after  mental  work.  These  secondary  results 
are  best  realized  when  there  is  no  activity  of  any  kind 
directly  after  the  physical  activity;  for  this  reason, 
it  is  well  to  have  the  exercise  come  at  the  end  of  the 
formal  school  instruction,  particularly  because  it 
then  satisfies  the  desire  for  movement  that  comes 
from  sitting  still  for  a  long  time.  If  the  exercise  be 
carried  out  with  less  intensity,  it  has  a  stimulating 
effect,  and  then,  but  only  then,  it  can  be  taken  be- 
tween, or  even  before,  the  period  of  formal  instruc- 
tion. 

Fatigue-coefficient  of  the  studies.  We  see,  then, 
that  gymnastics  and  similar  physical  activities  have 
a  special  relation  to  fatigue.  But,  in  the  same  way, 
every  discipline,  every  subject-matter,  has  its  own 


THE  LAWS   OF   TATIGUE  105 

peculiar  way  of  setting  the  mind  into  action,  and 
hence  the  fatigue-effect  is  different  for  each  of  them. 
One  of  the  special  chapters  in  the  investigation  of 
fatigue — Griesbach  is,  in  fact,  the  first  to  state  the 
problem — has  to  do  with  determining  which  subject 
fatigues  the  most  and  in  what  direction  the  most ;  in 
other  words,  with  determining,  at  least  quantita- 
tively, the  specific  degree  of  the  fatigue-effect  of  each 
study  (other  conditions  being  equal).  This  we  may 
term  the  fatigue-coefficient.  It  affects  the  outcome  of 
mental  work  as  the  friction  of  machines,  indicated  by 
their  coefficient  of  friction,  lessens  their  mechanical 
efficiency.  By  the  use  of  this  fatigue-coefficient,  there 
might  be  made  out  a  fatigue-scale  of  the  several 
school  subjects  that  could  apply  either  to  the  ability 
and  disposition  of  the  single  pupil  or  to  the  average 
capacity  of  an  entire  class,  and  to  a  given  age  or  stage 
of  development  as  well.  The  experience  of  the  school- 
room has  taught  us  for  a  long  time  that  certain 
studies  strain  and  fatigue  some  more  than  others  of 
the  pupils,  and  that  there  are  certain  lessons  and  cer- 
tain subjects  that  make  greater  demands  than  others 
upon  at  least  the  average  of  the  class.  The  results 
obtained  by  Griesbach  with  the  esthesiometer  accord 
pretty  well  with  this  schoolroom  experience,  as  they 
show  that  mathematics  and  memorization-exercises 
are  very  fatiguing,  much  more  so  than  geography  or 
draT\dng.  Similar,  though  not  identical  results  have 
been  obtained  by  Wagner,  Sakaki  and  Blazek,  with 
the  same  method,  and  by  Kemsies  with  the  ergograph 
(Deutsch.  Med.  WochenscJirift,  1896).  Both  Vannod 
and  Vaschide  showed  by  the  use  of  the  esthesiometer 
that  mathematics  and  ancient  languages  are  more 


106  MENTAL  FATIGUE 

fatiguing  than  geography  and  French  (here  the 
mother  tongue).  But  it  is  interesting  to  note  that 
Vannod  found  drawing  to  be  strongly  fatiguing,  also. 
Quite  in  accord,  again,  with  schoolroom  experience  is 
Eitter's  observation  that  exercises  in  sight  transla- 
tion are  more  exacting  than  the  reading  of  the  au- 
thors. There  is  no  reason  to  be  surprised  that  these 
experimental  results  do  not  show  more  exact  agree- 
ment when  we  consider  the  inequality  of  the  conduct 
of  class  instruction  and  of  the  requirements  of 
schools  of  different,  and  even  of  those  of  the  same 
type,  and  when  we  remember,  further,  that  the  meas- 
urements were  not  all  taken  by  the  same  method 
and  that  the  subjects  in  question  were  conducted  at 
different  lesson-periods  (before  or  after  a  pause, 
before  noon  or  after  noon,  at  the  beginning  and  at 
the  end  of  the  school  day),  and  that  this  discrepancy 
has  not  been  allowed  for.  There  are  also  involved 
here  certain  other  factors  that  we  shall  discuss  later. 
Afternoo7i  instruction.  The  specific  fatigue-effect 
of  afternoon  instruction  is  still  undetermined. 
Sakaki,  Vaschide  and  Vannod,  on  the  basis  of  their 
esthesiometric  tests,  made  out  that  afternoon  instruc- 
tion fatigues  much  more  than  forenoon  instruction. 
Similarly,  Schuyten  found  (Voor-  en  Nam)  that  in 
afternoon  sessions  more  errors  were  made  in  copying 
and  poorer  results  were  exhibited  in  learning  two- 
place  numbers.  But  it  is  not  certain  how  much  the 
physiological  factor,  digestion,  may  have  affected 
this  result.  We  may  assume,  on  the  other  hand,  that 
the  taking  in  of  nourishment  brings  with  it  a  restora- 
tion of  the  supply  of  energy.  The  ergograph,  and 
likewise  the  dynamometer  (Schuyten),  shows  that 


THE   LAWS   OF   FATIGUE  107 

bodily  strength  is  increased  thereby.  Eitter  con- 
cluded from  his  use  of  the  word-learning  method  that 
his  gymnasial  pupils  at  Ellwangen  were  somewhat, 
though  not  much  more  fatigued  by  a  two  to  three- 
hour  afternoon  session  than  by  a  four-hour  morning 
session.  It  depends  entirely  on  the  length  and  use  of 
the  noon  intermission. 

In  view  of  the  fact  that  the  time  from  4  or  5  o  'clock 
to  8  0  'clock  or  later  is  the  best  part  of  the  day  for  very 
many  mental  workers,  and  that  of  64  mathematicians 
who  replied  to  a  questionary,  24  asserted  that  the 
evening  was  their  best  time  for  work,  while  seven 
rated  morning  and  evening  as  equally  good  (Clapa- 
rede,  in  L'enseignement  math.,  1908,  pp.  216  f.),  we 
certainly  cannot  urge  any  theoretical  objections 
against  instruction  that  begins  late  in  the  afternoon, 
provided  care  be  taken  that  the  process  of  digestion 
is  entirely  finished.  Or,  if  we  may  disregard  entirely 
the  disputed  question  of  one-session  or  two-session 
plan  (a  question  complicated  by  other  and  quite  dif- 
ferent issues,  e.  g.,  possibility  of  adequate  physical 
activity,  distance  of  the  home  from  the  school,  time- 
consuming  and  wearying  trips  on  rail  and  street  cars, 
and  in  winter,  too,  the  problem  of  illumination,*  and, 
furthermore,  the  oversight  of  pupils  that  have  no 
afternoon  instruction  and  the  question  of  meal-hours 
as  they  are  affected  by  parental  occupation  and  other 
local  customs) — if  we  disregard  this  question,  we 
should  like  to  put  the  matter  quite  generally  by  say- 
ing: Eeadiness  for  mental  work  is  renewed  in  the 
second  part  of  the  day  at  two  to  three  hours  after 


♦Consult  the  judicious  treatment  of  the  question  in  Burgerstein, 
578  ff.,  and  in  Treutlein's  Progr.  d.  Realgymn.,  Karlsruhe,  1906. 


108  MENTAL  FATIGUE 

eating  the  noon  meal.  This  second  work-period  is,  in 
fact,  more  favorable  than  the  morning  period  for 
many  persons  (Cf.,  also,  Schuyten,  Paed.  Jaarhoeh, 
VII).  The  most  satisfactory  plan  for  giving  proper 
weight  to  all  the  pertinent  factors  appears  to  be  to 
put  formal  school  exercises  so  far  as  possible  in  the 
forenoon,  to  use  the  afternoon  for  comprehensive, 
but  not  formal  physical  activity,  and  then,  after  a  rest 
of  half  an  hour  to  an  hour,  with  nourishment,  to  de- 
vote the  evening  hours  from  5  to  8  to  mental  work 
again,  using  this  time  for  the  pupils^  studies,  for 
reading,  and  for  review  and  preparation  of  home- 
work— the  abolition  of  which,  as  desired  by  many  per- 
sons, including  some  teachers,  would  not  be  at  all 
favorable  to  training  in  independent  mental  work; 
as  even  Kraepelin  {Ueherh.  37)  admits.  From  these 
considerations,  there  appears  justification  of  evening 
schools  for  apprentices,  for  whom,  as  a  rule,  such 
courses  are  more  of  a  recreation  than  an  exaction  of 
further  effort  (Schuyten).* 

School  program.  These  considerations  of  the  value 
of  forenoon  and  afternoon  sessions  and  of  the  fa- 
tigue-value of  the  several  studies  are  naturally  of  sig- 
nificance in  the  arrangement  of  the  school  program, 
as  well  as  for  the  choice  of  the  total  number  of  pe- 
riods, and  particularly  for  the  division  of  these 
periods.  We  shall  have  to  try  to  put  the  most  difficult 
subjects  in  the  first  two  periods  of  the  day,  to  put 
some  easier  subjects  between  difficult  subjects,  and  to 
put  gymnastics  at  the  end  of  the  forenoon  session,  or 

*See,  however,  Winch,  Some  measurements  of  mental  fatigue  in 
adolescent  pupils  in  evening  schools,  Jour.  Educ.  Psychol.  I,  1910, 
13-24,  83-100, where  different  conclusions  are  reached.^— Translator. 


THE  LAWS   OF   FATIGUE  109 

even  better,  to  defer  these  imtil  the  afternoon,  as  had, 
indeed,  been  done,  so  far  as  feasible,  in  many  places, 
before  these  questions  were  attacked  by  experimen- 
tal investigation.  One  of  the  worst  obstacles  encoun- 
tered in  the  attempt  to  make  such  arrangements  is 
the  system  of  departmental  instruction. 

Schiller  (1897)  was  the  first  to  try  to  adjust  a 
school  program  in  conformity  with  the  results  of  ex- 
perimental psychology.  But  it  is  clear  that  this  was 
only  a  preliminary  attempt,  which  did  not,  and  could 
not,  claim  to  afford  an  ultimate  solution.  The  inves- 
tigations of  the  fatigue-value  of  the  several  studies 
are  still  far  from  reaching  results  that  are  in  any 
way  conclusive.  Nor  can  they  ever  afford  us  univer- 
sally valid  conclusions.  Strictly  interpreted,  even 
when  the  difficulty  of  the  fatigue- effect  at  different 
hours  is  obviated  by  making  a  large  number  of  ex- 
periments, they  are  valid  only  for  the  average  of  a 
class  actually  compounded  of  good,  average  and  poor 
pupils,  animated  by  varied  specific  lines  of  interest. 
But  this  changes  in  proportion  as  this  composition  of 
the  class  changes  by  entrance  or  loss  of  pupils  and  in 
proportion  as  the  pupils  themselves  change,  for  we 
must  remember  that  their  mental  development  does 
not,  in  any  case,  proceed  with  entire  uniformity.  Fur- 
thermore, the  results  must  differ  in  other  classes  that 
differ  in  composition  according  to  the  endowment 
and  propensities  of  the  pupils.  And  it  is  well  known, 
too,  that  the  same  subject  is  not  equally  difficult  in 
every  class — that,  for  instance,  the  geography  of  Ger- 
many, which  is  the  assignment  for  the  first  and  sec- 
ond classes  of  the  Gymnasium,  makes  very  much  less 
demand  on  the  pupil,  at  least  when  skillfully  man- 


110  MENTAL  FATIGUE 

aged,  than  the  geography  of  countries  outside  of  Eu- 
rope, which  is  assigned  in  the  fourth  class,  and  which 
is  commonly  compressed  into  a  single  year's  work. 
So  we  cannot  simply  say :  geography  is  less  fatiguing 
than,  perhaps,  a  lingTiistic  study.  Then,  again,  a 
school  lesson  is  more  exacting  if  the  number  of  pu- 
pils in  the  class  is  small,  because  then  the  pupils  are 
called  on  oftener  and  have  to  know  their  lesson 
better. 

Fatigue-coefficient  of  the  teacher.  One  more  fac- 
tor, is  to  be  noted  that  appreciably  complicates  the 
determination  of  the  fatigue-coefficient  of  any  study, 
namely,  the  fatigue-coefficient  of  the  teacher.  The 
more  stimulating  is  a  teacher 's  instruction,  the  more 
skillful  he  is  in  riveting  the  attention  of  his  pupils, 
the  more  fatiguing  is  his  instruction.  The  interest 
aroused  by  the  teacher  may  banish  the  feeling  of 
fatigue  in  the  pupils,  but,  as  Griesbach  {Intern. 
Archiv.,  V)  properly  remarks,  this  interest  can  as  lit- 
tle remove  the  actual  fatigue  of  the  pupils  as  can  the 
music  of  the  regimental  band  banish  the  fatigue  of  a 
marching  troop.  This  everyday  observation  has  been 
confirmed  by  Wagner  {Unterricht  und  Ermudung, 
115  ft'.)  by  means  of  esthesiometric  tests.  And  he  is 
right  when  he  estimates  this  factor  as  of  more  impor- 
tance than  the  fatigue-value  of  the  subject-matter. 
Moreover,  a  teacher  who  has  little  capacity  for  sus- 
taining his  pupil's  attention  can  compel  them  to  more 
active  participation  by  harsh  disciplinary  measures. 
In  such  cases,  the  pupils  exert  their  whole  energ\^ 
from  fear. 

Fatigue-coefficient  of  the  method  of  teaching  and 
learning.      Besides    the    fatigue-coefficient    of    the 


THE   LAWS   OF   FATIGUE  111 

teacher  and  that  of  the  subject-matter,  there  is  also 
a  fatigue-coefficient  of  the  method  of  teaching  and 
learning.  Thus  far  scarcely  any  attempt  has  been 
made  to  evaluate  it;  only  Eulenburg  and  Bach  (p. 
1239)  mention  it.  But  it  is  evident  that,  even  from 
the  standpoint  of  the  economy  of  mental  force,  it  is 
not  a  matter  of  indifference  whether  I  acquire  certain 
information,  e.  g.y  in  the  history  of  civilization,  in 
botany,  in  physics,  or  in  chemistry,  by  merely  listen- 
ing to  a  verbal  description,  or  by  reading  about  it,  or 
by  observation.  Again,  in  the  observation  itself  it  is 
not  a  matter  of  indifference  whether,  in  my  consider- 
ation of  the  object  or  of  the  pictorial  representation 
of  it,  I  am  guided  by  an  accompanying  description 
of  the  teacher,  or  whether  I  have  quite  by  myself  to 
pick  out  the  essential  features  and  separate  them 
from  the  unessential  ones.  And  it  certainly  makes 
some  difference  in  the  demands  on  mental  efficiency 
whether  a  poem  or  a  prose  selection  is  learned  by 
heart  without  adequate  explanation  of  its  meaning, 
or  only  after  there  has  been  gained  complete  under- 
standing and  adequate  survey  of  the  thing  as  a  whole 
and  after  some  emotional  reaction  has  thus  been 
awakened  for  the  piece.  Again,  it  will  make  a  dis- 
tinct difference  whether  a  principle  in  physics  has 
chanced  to  be  worked  out  deductively  and  developed 
by  mathematical  formulas,  or  whether  it  has  been  dis- 
covered inductively  by  the  introduction  of  experi- 
ments, whether  the  course  of  thought  of  a  problem  in 
philosophy,  ethics,  or  natural  science  has  been  sim- 
ply assimilated  in  a  purely  receptive  manner,  or  has 
been  developed  by  means  of  free  exchange  of  ideas 
between  pupils  and  teacher.    These  statements  are, 


112  MENTAL  FATIGUE 

of  course,  only  opinions.  In  general,  the  problems 
that  are  raised  by  them  are,  unfortunately,  in  large 
measure  so  complex  in  nature  that  their  solution  by 
experiment  is  still  a  far-distant  matter.  Meantime, 
we  must  rely  for  the  working  out  of  such  problems 
entirely  upon  the  keen  sensitivity  of  the  teacher  who 
keeps  watch  on  the  effects  of  his  teaching. 

Individual  instruction  and  class  instruction.  It 
is  also  clear  that  the  economy  of  mental  energy  is  dif- 
ferent in  individual,  from  that  in  class  instruction, 
and  that  this  difference  plays  a  very  decisive  influ- 
ence in  the  division  of  the  subject-matter  and  the  ar- 
rangements of  the  school  program.  Class  instruc- 
tion makes  distinctly  fewer  demands  on  the  attention 
of  the  pupils,  for  it  permits  those  pupils  who  are  not 
actually  called  on  for  recitation  to  work  at  half-atten- 
tion. Kraepelin  {Geistige  Arbeit,  18)  sees  in  this 
very  fact  a  safety-valve,  an  automatic  protective  de- 
vice against  the  over-exactions  of  the  school.  If,  he 
means,  the  pupil  were  compelled  to  work  at  maximal 
attention  during  the  whole  school  session,  he  would 
break  down.  But,  as  we  have  already  asserted  once 
before,  class  instruction  does  not  really  presuppose 
this.  Because,  if  it  could  ever  be  brought  about  that 
the  pupils  followed  the  whole  lesson  with  undivided 
attention,  then  we  could  certainly  get  on  with  a  much 
shorter  school  session.  Indi^ddual  instruction  dem- 
onstrates the  truth  of  this  statement.  But,  since  the 
school  cannot  compel  this  intensive  concentration  of 
attention,  it  must  extend  the  duration  of  the  school 
day  to  make  up  for  it.  From  the  point  of  view  of  the 
teacher,  however,  the  relations  are  just  the  reverse. 
For  him,  individual  instruction  is  much  less  exacting 


THE  LAWS  OF  FATIGUE  113 

than  class  instruction,  whicli,  as  the  class  increases  in 
size,  demands  that  just  so  much  louder  speech  and 
just  so  much  more  careful  watching  of  the  behavior 
and  of  the  attention  of  the  pupils  be  added  to  the  task 
of  teaching  itself.  The  most  exacting  kind  of  school 
work,  as  is  well  known,  is  preparation  for  an  exam- 
ination; this  Griesbach  has  demonstrated  by  tests 
with  the  esthesiometer. 

FatiguahUity  of  the  teacher.  This  leads  us  now  to 
speak  briefly  of  the  teacher,  since  we  have  thus  far 
treated  almost  exclusively  of  the  fatigue  of  pupils. 
We  noted  once  before  that  fatiguability  reaches  its 
minimum,  or  mental  efficiency  its  maximum,  at  the 
beginning  of  the  twenties.  If  other  conditions  are 
favorable,  we  appear  to  remain  in  this  stage  some 
ten  or  fifteen  years,  often  still  longer.  As  we  reach 
our  fourth  decade,  efficiency  slowly  declines,  and  f rom. 
the  age  of  50  on,  this  decline  becomes  quite  manifest 
in  many  persons.  From  this,  the  conclusion  may  be 
drawn  that  the  teacher — like  every  mental  and  physi- 
cal worker — ought,  as  he  grows  older,  to  have  his 
load  lightened,  not  increased,  as  is  at  present  so  often 
the  case :  thus,  for  example,  the  teachers  of  the  two 
upper  classes  (the  two  Prima),  who  are  frequently 
the  oldest  of  the  staff,  often  have  the  hardest  work — 
with  the  possible  exception  of  the  teachers  of  the  fifth 
and  sixth  classes  (the  two  Tertia).  The  opposite  ar- 
rangement would  be  more  rational  from  the  stand- 
point of  economy  of  energy.  Basing  their  action  on 
this  same  argument,  the  Austrian  association  of 
teachers  of  the  middle  schools  has  incorporated  into 
their  program  a  movement  for  the  reduction  of  hours 
of  service  as  the  age  of  the  teacher  increases — a  posi- 


114  MENTAL   FATIGUE 

tion  for  wMch  Burger  stein  (p.  721)  has  pleaded  for  a 
long  time.  It  must  be  admitted  that  in  Bavaria,  as 
the  work  is  now  distributed,  there  can,  in  general,  be 
no  complaint  that  the  teachers  are  overburdened,  at 
least  so  far  as  the  number  of  hours  of  required  in- 
struction are  concerned.  And  it  is  not  only  the  right, 
but  the  duty  of  those  in  charge  of  the  schools  to  take 
proper  steps  to  insure  that  the  teachers  do  not  ex- 
haust their  energies  all  too  soon  by  giving  extra  in- 
struction outside  the  required  school  hours.  The 
maximal  number  of  pupils  for  the  middle  and  upper 
classes  seems,  however,  to  be  too  great,  when  we  con- 
sider the  labor  of  correcting  the  pupils '  work,  and  this 
becomes  particularly  important  in  the  cases,  which 
are  many,  in  which  the  regular  enrollment  is  the  max- 
imal number  allowed.  In  the  matter  of  number  of 
hours,  only  the  teachers  of  the  fourth  and  fifth  classes 
are  overloaded  in  schools  in  which,  as  is  still  quite 
often  the  case,  they  carry  all  the  class  instruction 
save  that  in  mathematics. 

But  even  when  the  maximally  permissible  number 
of  hours  are  not  assigned,  the  academically  trained 
teacher  nevertheless  finds  that  his  capacity  for  work 
is  well  taxed,  more  so  than  in  most  other  academic 
callings.  Here,  as  ever,  exceptions  prove  the  rule. 
Unstinted  praise  belongs  to  H.  Schroder  for  having 
proved  incontestably  by  statistical  inquiry  that  the 
notion  that  the  teacher,  on  account  of  his  constant 
association  with  youth,  rejoices  in  unusual  vitality  is 
a  naive  fable,  that,  as  a  matter  of  fact,  the  academi- 
cally trained  teacher,  in  particular,  exhausts  his  pow- 
ers sooner  than  do  other  officials  of  like  training,  and 
that  his  Liability  to  disease  and  his  mortality  exceeds 


THE  LAWS  OF  FATIGUE  115 

that  of  other  public  servants.  Subsequent  inquiries 
have  showed  that  he  was  right.  The  teacher  of  the 
Volhssclmle  works  under  still  more  unfavorable  con- 
ditions.* From  a  purely  business  point  of  view, 
therefore,  the  teacher  ^s  capacity  to  work  should  be 
economized,  to  the  end  that  it  may  be  rendered  avail- 
able for  longer  service.  To  say  nothing  at  all  of  the 
enormous  importance  for  the  success  of  teaching  and 
education  that  the  teacher  shall  confront  his  pupils 
with  perfect  freshness  of  mind  and  spirit,  not  with 
the  irritability  and  ill-humor  of  a  neurasthenic. 


*Cf.  R.  Wichmann's  lecture  on  the  health  of  teachers  in  the  Yer- 
Tiandlungen  der  VII.  Jahresversammlung  des  deutschen  Vereines 
fur  8chulgesu7id7ieitspflege,  1906,  at  Dresden,  also  the  Ergdnzung- 
sTieft  to  Gesunde  Jugend,  Yl,  1906,  27  ff.,  and  the  very  noteworthy- 
chapter  on  the  hygiene  of  the  teacher  in  Burger  stein,  718  ff.,  as 
well  as  L.  Wagner's  comments  in  his  translation  of  M.  V.  Mana- 
ceine's  Le  surmenage  mental  daiis  la  civilisation  moderne. 


CONCLUSIOIN 

There  are  many  other  questions  that  may  be  raised 
in  connection  with  this  subject.  And  we  might  at- 
tempt, in  summarizing,  to  work  out  a  unitary  theory 
of  fatigue.  But  this  would  be  possible  only  by  dis- 
cussing the  general  energetics  of  mental  life,  the  gen- 
eral theory  of  the  forces  operative  in  our  psychical 
life,  their  amounts,  their  origins,  their  consumption, 
and  the  laws  of  their  interaction.  We  have  been  led, 
indeed,  to  do  this  on  more  than  one  occasion,  as,  for 
instance,  when — in  our  earlier  presentation  of  the 
problem  of  memory  along  Lippsian  lines — we  made 
use  of  the  concept  of  mental  energy  and  its  supply, 
and  when  we  said  of  it  that  it  increases  with  rest  and 
nutrition,  but  is  used  up  during  work.  But  it  would 
lead  us  farther  into  the  field  of  psychological  theo- 
ries and  hypotheses  than  would  fit  the  purpose  of  the 
present  discussion  were  we  to  pursue  these  consider- 
ations any  longer. 

75  it  permissible  that  pupils  he  fatigued?  But  we 
must  first  answer  another  question  of  importance  to 
the  teacher.  Is  it  permissible  that  pupils  should  be 
fatigued  by  work,  or  more  exactly,  since  there  is  no 
work  of  any  sort  that  does  not  fatigue,  is  it  permis- 
sible that  pupils  should  be  held  to  their  work  so  long 
that  positive  signs  of  fatigue,  especially  weariness 
and  reduction  of  ivork,  appear? 

116 


CONCLUSION"  117 

Perhaps  this  question  will  be  answered  by  an  anx- 
ious negative,  for  fear  lest  the  youthful  nervous  sys- 
tem might  otherwise  suffer  injury,  and  it  will  be  cer- 
tainly pointed  out  that  the  work  that  is  done  under 
the  stress  of  oncoming  fatigue  is  surely  of  less  value. 

We  need  not  be  too  anxious,  even  if  we  do  not  stop 
to  note  that  a  piece  of  work  done,  though  it  may  be 
inferior  to  some  other,  is  nevertheless  better  than 
none  at  all.  So  long  as  the  youthful  worker,  by  dint 
of  adequate  nutrition  and  abundant  rest,  especially 
plenty  of  sleep,  regains  every  morning  his  capacity 
for,  and  pleasure  in,  work,  so  long  there  is  no  danger, 
and  we  may  unconcernedly  let  him  work  till  he  is 
fatigued.  Only,  we  should  not  neglect  at  the  same 
time  to  make  clear  to  him  the  significance,  as  a  pro- 
tector of  his  health,  of  the  feeling  of  weariness,  and 
to  train  him  in  this  way  to  restore  his  powers  and  to 
recuperate  his  energy  rationally. 

But  I  go  farther  than  this.  We  may,  indeed  we 
ought,  off  and  on,  to  let  him  work  a  good  bit  under 
the  pressure  of  fatigue.  We  ought,  now  and  then,  to 
induce  him  to  take  himself  in  hand  and  to  draw  on  all 
his  reserve  strength,  so  as  to  force  him,  as  a  test  of 
power  and  strength  of  will,  to  do  more  than  he  ordi- 
narily does.  Often  enough,  our  life  brings  us  into 
situations  where  we  have  to  put  forth  more  than  our 
customary  effort — situations  that  oblige  us  for  some 
time,  and  unfortunately  often  for  no  short  time, 
either,  to  turn  a  deaf  ear  to  the  kindly  warnings  of 
that  faithful  guardian  of  our  health. 

A  man  must  be  trained  to  meet  such  situations  as 
these,  too.  He  must  learn  by  his  own  experience  how 
much  strength  he  has  laid  by,  in  saving,  for  emergen- 


118  MENTAL.  FATIGUE 

cies ;  but  he  must  also  learn  as  well  how  to  expend  this 
reserve  prudently,  and  how  he  can  restore  it  once 
more.  To  learn  the  first  lesson  brings  him  assurance 
and  consciousness  of  power ;  to  learn  the  second  de- 
ters from  foolish  use  of  his  reserve  capital.  To  shield 
the  pupil  from  these  tests  of  strength  is  to  rear  him 
in  weakness  and  timidity.  And  in  this  sense,  we 
agree  with  Zielinski  when  he  says :  ^^  An  easy  school 
is  a  social  crime''  (see  Hofler,  39  f.). 

In  the  same  way,  physical  training  develops  in  the 
growing  being  the  capacity  for  resistance  that  is 
requisite  for  life,  not  by  timidly  sheltering  him  from 
the  harslmess  of  the  elements,  but  by  gradual  habitu- 
ation to  them,  by  a  process  of  hardening.  In  this 
physical  training,  he  is  compelled — ^not  every  day, 
but  from  time  to  time — to  undertake  trying  marches 
and  fatiguing  athletic  games,  to  endure  thirst  and 
hunger,  heat  and  cold,  weariness  and  pain  of  limb, 
to  exercise  self-control  by  deferring  the  gratification 
of  his  desires  (perfectly  justifiable  intrinsically)  un- 
til the  resting  place  has  been  reached,  the  journey's 
end  attained.  Then,  to  be  sure,  he  is  allowed  to  re- 
store himself,  but  he  is  taught,  even  then,  to  choose 
the  proper  kinds  of  food,  to  observe  moderation,  and 
to  take  his  repose  in  a  rational  manner.  And  if  we 
do  this  systematically  and  with  due  deliberation,  if 
we  bring  up  our  youth  to  proper  care  of  their  bodies, 
more  by  strict  training  than  by  fine  talking,  we  know 
that  we  are  thereby  doing  them  a  greater  kindness 
than  if,  out  of  weak  sympathy,  we  had  let  them  give 
heed  to  every  trivial  call  of  their  bodily  needs. 

Training  in  mental  hygiene.  Now,  training  in 
mental  hygiene  must  follow  precisely  the  same  plan, 


CONCLUSION  119 

if  it  is  to  train  up  hardy  and  persistent  workers,  and 
not  dawdling  weaklings,  in  the  fields  of  mental  effort. 
It  must  occasionally  exact  a  hard  bit  of  work  of  the 
youth.  It  is  to  be  assumed,  however,  that  it  will  make 
these  demands  of  him  only  when  it  can  afford  him  a 
proportionately  longer  time  for  subsequent  rest  and 
recovery,  and  when,  moreover,  it  teaches  him  method- 
ically how  the  stint  that  is  set  may  be  done  with  the 
available  amount  of  strength,  and  how  he  may  work 
most  economically  and  with  maximal  profit.  This 
kind  of  training  in  mental  hygiene  is  peculiarly  neces- 
sary in  these  days,  when  large  numbers  of  our 
youths,  especially  in  the  cities,  no  longer  bring  with 
them  to  the  school  the  same  unweakened  nervous  en- 
ergy that  our  father  and  grandfathers  displayed,  when 
life  outside  the  school  makes  greater  demands  on  the 
pupils  than  formerly,  and  when,  too — we  must  not 
deceive  ourselves  on  the  point — the  requirements  of 
the  school,  despite  the  fact  that  many  a  grammar  has 
become  thinner,  are  certainly  not  less,  when  they  are 
all  fully  satisfied,  than  they  were  forty  or  fifty  years 
ago.  For  our  school  work  today,  as  Keller  rightly 
declares,  is  less  restricted  and  unitary,  and  to  be  sure 
less  monotonous,  too,  but  rather  of  a  kind  to  appeal 
to  more  varied  interests ;  it  is  richer  in  content  and 
more  intensive  in  treatment,  since  it  proceeds  less 
mechanically,  less  by  mere  passive  reception,  but  im- 
pels the  entire  person  to  greater  activity. 

More  intensive  physical  development.  In  point  of 
fact,  the  school  cannot  stop  short  at  this  training  in 
mental  hygiene.  It  will  ultimately  be  compelled  in 
some  measure  to  reduce  its  scholastic  requirements, 
in  order  to  give  an  opportunity  for  a  serious  and  sys- 


120  MENTAL  FATIGUE 

tematic  plan  of  physical  development.  For  it  cannot 
be  denied  that  our  cultured  classes  are  now  retro- 
grading physically,  and  this  means  that  ultimately 
they  will  lose  in  mental  efficiency  as  well.  The  school 
is  certainly  much  less  to  blame  for  this  condition  of 
affairs  than  people  are  apt  to  think.  Only  an  excep- 
tionally strong  nervous  system  can  withstand  our 
complex  life,  ever  becoming  more  intensive,  the  de- 
mands of  our  professional  and  our  public  career,  as 
well  as  the  manifold  claims  arising  from  other  aspects 
of  our  life — claims  that  we  might  avoid  if  we  wished, 
but  to  which  we  tend  more  and  more  to  give  way  from 
lack  of  moral  force  to  decline  them.  Most  of  us  suf- 
fer, and  our  nervous  vigor  is  seriously  impaired  by 
this  stress  of  life. 

Nor  is  this  all.  The  weakness  of  the  parents  is 
handed  down  as  a  handicap  of  inheritance  to  the  chil- 
dren. These  are  facts  to  which  we  cannot  close  our 
eyes.  Eather  must  we  keep  the  situation  clearly  be- 
fore us,  and  use  every  endeavor  to  better  faulty  con- 
ditions. 

The  edict  of  the  Bavarian  ministry  of  public  in- 
struction, which,  several  years  ago,  required  the  cul- 
tivation of  athletic  games,  has  shown  the  right  road. 
We  need  only  keep  on  in  this  direction.  We  must 
make  participation  in  games  a  duty,  so  that  no  pupils, 
at  least  none  of  those  who  need  them  most,  the  weak- 
lings, can  fail  to  take  part  in  them.  And  we  must 
make  room  for  such  games  in  our  school  program  by 
reducing  the  demands  for  intellectual  work,  so  that 
even  the  most  industrious  and  conscientious,  who  are 
the  very  ones  that  stand  most  in  need  of  a  counter- 
act ant  to  their  mental  effort,  shall  be  able  to  indulge 


COI^CLTJSION  121 

in  games  with  an  easy  conscience  and  with  no  lack 
of  enthusiasm.* 

Finally,  we  must  undertake  seriously  to  revise  our 
views  of  the  relation  of  bodily  and  mental  work.  We 
must  reach  the  conviction  that  bodily  life  and  mental 
life  are  not  separate  systems,  but  that  they  spring 
from  the  same  sources ;  that  they  do  not  keep  separate 
accounts,  like  married  folks  who  divide  their  goods, 
but  work  together,  like  husband  and  wife  who  hold 
the  funds  in  common,  when  whatever  the  one  takes 
out  of  the  bank  is  no  longer  at  the  disposal  of  the 
other. 

If  this  exposition  assists  teachers  to  a  fuller  under- 
standing of  the  close  connections  between  the  two 
sides  of  our  human  nature  and  of  the  limits  of  their 
efficiency,  and  if  it  stimulates  them  to  make  applica- 
tion of  this  understanding,  it  will  have  served  its 
purpose. 


*0n  the  lack  of  adequate  participation  in  athletic  games,  con- 
sult Dornberger  (Dtsch.  Med.  Prax.,  13)  and  Grassmann  (p.  170), 
who  demands  compulsory  participation  to  remedy  this  faulty  con- 
dition. 


BIBLIOGRAPHY. 

(For  selected  English  references,  see  Appendix  I,  below). 

Key  to  Symbols. 

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A.  J.  P. — American  Journal  of  Psychology. 

A.  J.  Ph. — American  Journal  of  Physiology. 

A.  P. — Annee  psycho logique. 

Ar.  P. — Archives  de  Psychologie. 

I.  M. — International  Magazine  of  School  Hygiene. 

I,  K. — Internationaler  Kongress. 

J.  E.  P. — Journal  of  Educational  Psychology. 

P.  A. — Psychologische  Arbeiten. 

P.  J. — Paedologisch  Jaarboek. 

P.  R. — Psychological  Review. 

P.  S. — Pedagogical  Seminary. 

Ph.  S. — Philosophische  Studien. 

S.  Z. — Sciiiller-Ziehen,  Sammlung  von  Abhandlungen  aus  dem 
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Z.  P. — Zeitschrift  fiir  Psychologie  und  Physiologic  der  Sinnes- 
organe. 

Z.  P.  P. — Zeitschrift  fiir  padagogische  Psychologie. 

Z.  S. — ^Zeitschrift  fiir  Schulgesundheitspflege. 


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F.  Galton,  La  fatigue  mentale,  in  Revue  scientifique,  17 :  1889. 
R.  Gaupp,  Psychologie  des  Kindes.    2d  ed.,  1910. 
J.  B.  Germann,  On  the  invalidity  of  the  esthesiometric  method  as  a 

measure  of  mental  fatigue,  in  P.  R.,  6 :  1899. 


124  MENTAIi  FATIGUE 

D.  Gineff,  Priifung  der  Methoden  zur  Messung  geistiger  Ermiidung. 

1899.     (Dissertation.    Ziirich.) 
K.  Grassmann,  Spielnachmittage,  in  Der  Arzt  als  Erzieher,  4 :  1908. 
H.  Griesbach,   Energetik  und  Hygiene  des  Nervensystems  in  der 

Schule.    1895. 
H.  Griesbach,  Weitere  Untersuchungen  uber  Beziehungen  zwischen 

geistiger  Ermiidung  und  Hautsensibilitat,  in  I.  M.,  1 :  1905. 
H.  Griesbach,  Einheitliche  Gestaltung  des  hoheren  Unterrichts  von 

physiologischen    und    hygienischen    Gesichtpunkten    aus    be- 

trachtet,  in  Verhandlungen  der  IX.     Jahresversammlung  des 

allgemeinen    deutschen    Vereins    ftir    Schulgesundheitspflege, 

in  Darmstadt.     (Gesunde  Jugend,  1908,  Erganzungshef t. ) 
H.  Griesbach,  Himlokalisation  und  Ermiidung,  in  Archiv  f.  d.  ges. 

Physiologie,  181 :  1910. 
Th.   Heller,   Ermiidungsmessungen   an  schwachsinnigen  Schulkin- 

dern,  in  Wiener  Medizinische  Presse,  40 :   1899. 
V.  Henri,  see  Binet  and  Tawney. 
G.   Herberich  und  K.   Schmid-Monnard,  Thesen  zur  Schulreform 

und   Unterrichtshygiene,   in   Verhandlungen   der   Gesellschaft 

Deutscher  Naturforscher  und  Aerzte.     71  Vers.,  zu  Miinehen, 

1899.     II.  T.,  1.    Halfte. 
L.  Hermann,  Lehrbuch  der  Physiologie.    11th  ed.,  1896. 
G.  Heiimann,  Ueber  die  Beziehungen  zwischen  Arbeitsdauer  und 

Pausenwirkung,  in  P.  A.,  4:  1904. 
L.  Hirschlaff,  Zur  Methode  und  Kritik  der  Ergographenmessungen, 

in  Z.  P.  P.,  3 :  1901. 
A.  Hoch  und  E.  Kraepelin,  Ueber  die  Wirkung  der  Teebestandteile 

auf  die  geistige  und  korperliche  Arbeit,  in  P.  A.,  1 :  1896. 
A.  Hofler,  Didaktik  des  mathematischen  Unterrichts,  1910.    (Didak- 

tische  Handbiicher  fur  den  realistischen   Unterricht  an  den 

hoheren  Schulen,  herausgegeben  von  A.  Hofler  und  F.  Poske, 

Bd.  I.) 
L.  Hopfner,  Die  geistige  Ermiidung  von  Schulkindern,  in  Z.  P.,  6 : 

1894. 
M.  E.  Holmes,  The  fatigue  of  a  school  hour,  in  P.  S.,  3 :  1895. 
H.   Januschke,    Einige  Daten  zur   gesundheitsmassigen   Regelung 

der  Schulverhaltnisse,  in  Zeits.  f.  Realschulwesen,  19.     (Wien, 

1894.) 
J.  Joteyko,  Fatigue,  in  Richet's  Dictionnaire  de  Physiologie,  1903. 
J.  Joteyko,  Les  lois  de  I'ergographie,  in  Bull,  de  I'Acad.  Belg.  CI.  d. 

sciences,  Nr.  5.    1904. 
R.  Keller,  Padagogisch-psychometrische  Studien,  in  Biol.  Zentral- 

blatt,  14 :  1894 ;  17 :  1897. 
R.  Keller,  Experimentelle  Untersuchungen  liber  die  Ermiidung  von 

Schiilern  durch  geistige  Arbeit,  in  Zeits.  f.  Schulhygiene,  10: 

1897. 
R.  Keller,  Ueber  den  40-Minutenbetrieb  des  Gymnasiums  und  der 

Industrieschule  in  Winterthur,  in  I.  M,,  2 :  1906. 
Fr.   Kemsies,   Zur  Frage  der   Ueberbiirdung,   in   Deutsche  Medi- 
zinische Wochenschrift,  22 :  1896. 


EIBLIOGEAPHY  125 

Fr.  Kemsies,  Arbeitstypen  bei  Schtilern,  in  Z.  P.  P.,  3 :  1901. 

Fr.  Kemsies,  Arbeitsbygiene  der  Scbule  auf  Grund  von  Ermtidungs- 

messungen,  in  S.  Z.,  2 :  1898,  Heft  I. 
A.  Key,  Scbulbygieniscbe  Untersucbungen.    1889. 
E.  Kraepelin,  Psycbiscbe  Disposition,  in  Arcbiv  fur  Psycbiatrie, 

25 :  1893 ;  also  in  Neurologiscbes  Zentralblatt,  12 :  1893. 
E.  Kraepelin,  Geistige  Arbeit    1894.     (4tb  ed.,  1903)  Aus  Heidel- 

berger  Jahrbucber,  4 :  1894. 
E.  Kraepelin,  Zur  Hygiene  der  Arbeit.    1896. 
E.  Kraepelin,  Zur  Ueberbiirdungsfrage.     1897. 
E.  Kraepelin,  Ueber  die  Messung  der  geistigen  Leistungsfahigkeit 

und     Ermiidbarkeit,     in     Verbandlungen     der     Gesellscbaft 

Deutscher  Naturforscber  und  Aerzte.     70te  Versammlung  zu 

Dusseldorf,  1898.     II.  T.,  1  Halfte. 
E.  Kraepelin,  Die  Arbeitskurve,  in  Pb.  S.,  19 :  1902. 
E.  Kraepelin,  Ueber  Ermiidungsmessungen,  in  A.  G.  P.,  1 :  1903. 

See  also  Hoch,  Oseretzkowsky,  and  Rivers. 
O.  Kiilpe,  Grundriss  der  Psycbologie.    1893. 

L.  Landois,  Lebrbucb  der  Pbysiologie  des  Menscben.    Stb  ed.,  1893. 
H.  Laser,  Ueber  geistige  Ermiidung  beim  Scbulunterricbt,  in  Z.  S., 

7:  1894. 
W.  A.  Lay,  Experimentelle  Didaktik.    1893. 

J.  H.  Leuba,  On  tbe  validity  of  the  Griesbach  method  of  determin- 
ing fatigue,  in  P.  R.,  6 :  1894. 
E.  Lindley,  Arbeit  und  Rube,  in  P.  A.,  3 :  1901. 
Th.  Lipps,  Leitfaden  der  Psycbologie.    2d  ed.,  1906. 
M.  Lobsien,  Ueber  die  psychologiscbe-padagogischen  Methoden  zur 

Erforschung  der  geistigen  Ermiidung,  in  Z.  P.  P.,  2 :  1900. 
M.    liObsien,    Ermiidung   und   Zeitschatzung,    in   Padagogisch-psy- 

cbologische  Studien,  4:  1903. 
J.     Loeb,     Muskeltatigeit    als    Mass    psychiseher    Tatigkeit,     in 

Pfliiger's  Arcbiv  f .  d.  ges.    Pbysiologie,  39 :  1886. 
E.  Meumann,  Vorlesungen  zur  Einfiibrung  in  die  experimentelle 

Padagogik  und  ibre  psycbologiscben  Grundlagen.    1907. 
K,  Miesemer.  Ueber  psycbiscbe  Wirkungen  korperlicber  und  geis- 

tiger  Arbeit,  in  P.  A.,  4 :  1904. 
A.  Moutcboulsky,  Quelques  rechercbes  sur  les  variations  de  la  sen- 
sibility cutanee.     Berne,  1900. 
A.  Mosso,  La  fatica.    1891.     (German  by  J.  Glinzer,  1892.) 
R.  Miiller,  Ueber  Mossos  Ergograph,  in  Pb.  S.,  17:  1901. 
P.  M.  Noikow,  Aestbesiometrische  Ermiidungsmessungen,  in  I.  M., 

4:  1907-8. 
A.   Oebrn,   Experimentelle  Studien  zur   Individualpsycbologie,  in 

P.  A.,  1 :  1896. 
M.  Offner,  Lipps'  Leitfaden  der  Psycbologie,  in  Z.  P.,  45 :  1908. 
M.  Ofener,  Das  Gedacbtnis.    1909. 
A.  Oseretzkowsky  und  E.  Kraepelin,   Beeinflussung  der  Muskel- 

leistung  durcb  vercbiedene  Arbeitsbedingungen,  in  P.  A.,  3: 

1901. 


126  METSTTAL   FATIGUE 

J.  Ranke,  Tetanus.    1865. 

G.  Richter,  Unterricht  und  geistige  Ermiidung,  in  Lehrproben  und 

Lehrgange,  45 :  1895. 
C.  Ritter,  Ermiidungsmessungen,  in  Z.  P.,  24 :  1900. 
W.  H.  R.  Rivers  und  E.  Kraepelin,  Ueber  Ermiidung  und  Erholung, 

in  P.  A.,  1 :  1896. 
E.  Romer,  Ueber  einige  Beziehungen  zwischen  Scblaf  und  geistigen 

Tatigkeiten,  in  Dritte  I.  K.  f.  Psyehologie,  in  Mtinchen,  1896. 
Y.  Sakaki,  Mitteilungen  iiber  Resultate  der  Ermudungsmessungen 

in  vier  Japanischen  Schulen  zu  Tokio,  in  1.  I.  K.  f.   Scliul- 

hygiene.     Niirnberg,  1904.    Bd.  II. 
H.  ScMller,  Der  Stundenplan.    1897.     (See  S.  Z.,  I.,  1.) 
E.  Schlesinger,  Aesthesiometrische  Untersuebungen  und  Ermiidungs- 
messungen  an   scbwacbbegabten    Schulkindern,    in   Archiv   f. 

Kinderbeilkunde,  41 :  1905. 
R.  Scbulze,  500,000  Reebenaufgaben :   eine  experimentelle  Unter- 

suebung,  in  Praktiscber  Scbulmann,  44:  1895. 
R.   Scbulze,  Aus  der  Werkstatt  der  experimentellen  Psycbologie. 

1909. 
M.  C.  Scbuyten,  Sur  les  metbodes  de  mensuration  de  la  fatigue  des 

gcoliers,  in  Ar.  P.,  2 :  1903. 
M.  C.  Scbuyten,  Comment  doit-on  mesurer  la  fatigue  des  4coliers, 

in  Ar.  P.,  4 :  1905. 
M.   C.   Scbuyten,  Onderzoekingen  over  estbesiometriscbe  variatie 

bij  kinderen  gedurende  bet  scbooljaar,  in  P.  J.,  5 :  1906-7. 
M.   C.   Scbuyten,   On   voor-en  namiddags  onderwijs,   in  P.   J.,   6: 

1907-8. 
M.  C.  Scbuyten,  Wat  is  over  lading?    Ontstaat  sij  door  een  te  veel  of 

door  eenzijdigelading?    In  P,  J.,  7:  1908-9. 
M.  C.   Scbuyten,  Estbesiometriscbe  onderzoekingen  op  volwassen 

leerlingen  die  een  avondkursus  folgen,  in  P.  J.,  7 :  1908-9. 
M.  C.  Scbuyten,  Mesure  de  la  fatigue  intellectuelle  cbez  les  enfants 

des  deux  sexes  avec  I'estbesiometre,  in  Revue  de  psychiatrie, 

1908,  taken  from  bis  Education  de  la  femme.    Paris,  1909. 
J.  Sikorski,  Sur  les  effets  de  la  lassitude  provoquee  par  les  travaux 

intellectuels  cbez  les  enfants  k  I'^ge  scolaire,  in  Ann.  d'byg. 

publ.,  2 :  1879. 
W.  Specbt,  Ueber  kliniscbe  Ermiidungsmessungen,  in  A.  G.  P.,  3: 

1904. 
W.  Stern,  Ueber  Psycbologie  der  individuellen  Differenzen.    1900. 
G.  Tawney  und  V.  Henri,  Die  Trugwabrnebmung  zweier  Punkte, 

in  Pb.  S.,  11 :  1895. 
O.  Teljatnik,  Review  in  Burgerstein  und  Netolitzky  (462  ff.)  of  his 

own    experiments,    published    first    in    Vjestnik    psichiatri- 

nevropatologi,  12:  1897  (St.  Petersburg). 
Tb.  Vanned,  La  fatigue  intellectuelle  et  son  influence  sur  la  sen- 

sibilite  cutanee,  in  Rev.  Med.  de  la  Suisse  Romande,  17 :  1897. 
Th.  Vanned,  La  metbode  estbesiometrique  pour  la  mensuration  de 

la  fatigue  intellectuelle,  in  Report  1st  Int.  Cong,  on  School 

Hygiene,  Niirnberg,  1904,  vol.  II. 


BIBLIOGEAPHY  127 

N.  Vaschide,  Les  recherches  experimentelles  sur  la  fatigue  intel- 

lectuelle,  in  Revue  de  Philos.,  5:  1905. 
M.  Verworn,  Allgemeine  Physiologie.    4th  ed.,  1903. 
L.  Wagner,  Unterricht  und  Ermiidungsmessungen  an  Schtilern  des 

neuen  Gymnasiums  in  Darmstadt,  in  S.  Z.,  1 :  1898,  Hft  4. 
L.  Wagner,  Die  geistige  Ueberbiirdung  in  den  hoheren  Sehulen,  in 

his  translation  of  Marie  v.  Manaceine,  Le  surmenage  mental 

dans  la  civilisation  moderne.    1905. 
W.  Weichardt,  Ueber  Ermiidungstoxine  und  Antitoxine,  in  Miinch- 

ener  Medizinische  Wochenschrift,  51 :  1904. 
W.   Weichardt,    Ueber   Ermiidungstoxine   und   deren   Hemmungs- 

korper.  Klinik,  2 :  1906. 
W.  Weygandt,  Ueber  den  Einfluss  des  Arbeitswechsels  auf  fort- 

laufende  geistige  Arbeit,  in  P.  A.,  2 :  1899. 
B.  Wichmann,  Der  Stand  der  akademisch  gebildeten  Lehrer  imd 

die  Hygiene,  in  Gesunde  Jugend,  6 :  1906,  Erganzungsheft. 
B.  Wichmann,  Die  Ueberbiirdung  der  Lehrinnen,  in  Kept.  1st  In- 
tern. Cong.  School  Hygiene,  Niirnberg,  1908. 
W.  H.  Winch,  Some  measurements  of  mental  fatigue  in  adolescent 

pupils  in  evening  schools,  in  J.  E.  P.,  1 :  1910,  13-24,  83-100. 

For  other  literature  on  the  fatigue  problem,  consult  Baade, 
Baginsky,  Burgerstein,  Claparede,  Dornberger  und  Wunderer, 
Eulenburg,  Gineff,  Joteyko  (Fatigue),  Meumann,  and  Kraepelin's 
works.* 

For  criticisms  of  the  methods  for  measuring  fatigue,  consult, 
besides  these  authors,  R.  Ttimpel,  Ueber  die  Versuche  die  geistige 
Ermiidung  durch  mechanische  Messungen  zu  untersuchen,  in  Zeits. 
f.  Philosophie  und  Padagogik,  5 :  1908,  J.  Larguier  des  Baneels, 
Essai  de  comparison  des  differentes  methodes  proposees  pour  la 
mesure  de  la  fatigue  intellectuelle,  in  A.  P.,  5 :  1899,  E.  L.  Thorn- 
dike,  Mental  fatigue,  in  P.  R.,  7 :  1900,  and  R.  Altschul,  Wert  der 
Bxperimente  bei  Schuluntersuchungen,  in  Rept.  1st  Intern.  Cong. 
School  Hygiene,  Niirnberg,  1904,  Vol.  II. 


*A  comprehensive  bibliograpliy  on  fatigue  up  to  the  year  1903,  prepared 
by  Mile.  Joteyko,  will  be  found  in  the  Dictionnaire  de  Physiologie.— 
Translator. 


APPENDIX    I. 

Selected  References  on  Fatigue  for  English  Readers. 

J.  A.  Bergstrom,  A  new  type  of  ergograph,  with  a  discussion  of 

ergographic  experimentation,  in  A.  J.  P.,  14 :  1903,  510-540. 
H.  G.  Beyer,  Ttie  relation  between  physical  and  mental  work,  in 

Jour.  Boston  Soc.  Med.  Sci.,  4 :  1900,  121-132. 
T.  Bolton,  The  reliability  of  certain  methods  for  measuring  the 

degree  of  fatigue  in  school  children,  in  P.  R.,  7 :  1900,  136-7. 
T.  Bolton  and  Eleanora  Miller,  On  the  validity  of  the  ergograph 

as  a  m-easm'er  of  work  capacity,  in  Nebraska  Univ.  Studies, 

1904,  79,  128, 

A.  C.  Ellis  and  Maud  Shipe,  A  study  of  the  accuracy  of  the  present 
methods  of  testing  fatigue,  in  A.  J.  P.,  14 :  1903,  496-509. 

S.  I.  Franz,  On  the  methods  of  estimating  the  force  of  voluntary 
muscular  contractions  and  on  fatigue,  in  A.  J.  Ph.,  4:  1900, 
348-372. 

F.  Galton,  see  Offner's  bibliography. 

C.  F.  Hodge,  Some  effects  of  electrically  stimulating  ganglion  cells, 
in  A.  .T.  P.,  2 :  1889,  376-402. 

Marion  E.  Holmes,  see  Offner's  bibliography. 

T.  Hough,  Ergographic  studies  in  neuro-muscular  fatigue,  in  A. 
J.  Ph.,  5 :  1901,  240-266. 

Wm  James,  The  energies  of  men,  in  Philos.  Rev.,  16 :  1907,  1-20. 

F.  S.  Lee,  Fatigue,  in  the  Harvey  Lectures,  Phila.,  1906,  169-194; 
also  in  J.  Amer.  Med.  Ass.,  46 :  1906,  1491,  and  in  Studies  in 
Physiology,  Columbia  University,  1902-7. 

F.  S.  Lee,  The  action  of  normal  fatigue  substances  on  muscle,  in 
A.  J.  Ph.,  20 :  1907,  170-179. 

F.  S.  Lee,  The  nature  of  fatigue,  in  Pop.  Sci.  Mo.,  76:  Feb.,  1910, 
182-195. 

J.  H.  Leuba,  see  Offner's  bibliography. 

W.  P.  Lombard,  The  effect  of  fatigue  on  voluntary  muscular  con- 
tractions, in  A.  J.  P.,  3 :  1890,  24-42. 

W.  P.  Lombard,  Some  of  the  influences  which  affect  the  power  of 
voluntary  muscular  contractions,  in  J.  of  Physiol.,  13 :  1892, 
1-58. 

A.  MacDonald,  Experimental  study  of  school  children,  etc.  Re- 
print of  chs.  21  and  25  of  Rept.  U.  S.  Comsnr.  of  Educ,  1899. 

W.  MacDougall,  On  a  new  method  for  the  study  of  concurrent  men- 
tal operations  and  of  mental  fatigue,  in  Brit.  J.  of  Psych.,  1 : 

1905,  435-445. 

W.  MacDougall,  The  conditions  of  fatigue  in  the  nervous  system,  in 

Brain,  Nov.,  1909,  256-268. 
H.  D.  Marsh,  The  diurnal  course  of  eflBciency,  Columbia  Univ.  diss., 

N.  Y.,  1906.    Pp.  99. 


128 


APPENDIX  I  129 


S.  W.  Mitchell,  Wear  and  tear,  or  hints  for  the  overworked.    5tli 

ed.,  Phila.,  1887.     Pp.  76. 
J.  M.  Moore,  Studies  in  fatigue,  in  Studies  from  the  Yale  Psych. 

Laboratory,  3:  1895,  68-95. 
A.  Mosso,  Fatigue.     Eng.  tr.,  N.  Y.,  1904.    Pp.  334. 
M.  V.  O'Shea,  Mental  fatigue,  in  Pop.  Sci.  Mo.,  55 :  1899,  511-524. 
W.  B.  Pillsbury,  Attention  waves  as  a  means  of  measuring  fatigue, 

in  A.  J.  P.,  14 :  1903. 
G.  T.  Patrick,  Fatigue  in  school  children:  a  review  of  the  experi- 
ments of  Friedrich  and  Ebbinghaus,  in  Univ.  of  Iowa  Studies 

in  Psych.,  1 :  1897,  77-86. 
W.  H.  Rivers,  On  mental  fatigue  and  recovery,  in  J.  of  Mental 

Science,  42:  1896,  525-529. 
C.  E.   Seashore,  A  method  of  measuring  mental  work :  the  psy- 

cherograph,  in  Univ.  of  Iowa  Studies  in  Psych.,  3 :  1902,  1-17. 
C.   E.    Seashore,   The  experimental   study   of  mental   fatigue,   in 

Psych.  Bulletin,  1 :  1904,  97-101. 
C.  E.  Seashore  and  G.  H.  Kent,  Periodicity  and  progressive  change 

in  continuous  mental  work,  in  P.  R.  Mon.  Supp.,  No.  28 :  1905, 

46-101. 
C.  S.  Sherrington.  The  integrative  action  of  the  nervous  system, 

N.  Y.,  1906.    Especially  214-221. 
F.  W.  Smedley,  Rept.  dept.  child-study  and  pedagogic  investigation, 

Chicago,   1898-1899   and   1899-1900.     Also  reprinted  in  Rept. 

U.  S.  Comsnr.  of  Educ,  1902,  vol.  1. 
Carrie  R.  Squire,  Fatigue:  suggestions  for  a  new  method  of  in- 
vestigation, in  P.  R.,  10 :  1903,  248-267. 
T.  Storey,  The  influence  of  fatigue  upon  the  speed  of  voluntary 

contraction  of  human  muscle,  in  A.  J.  Ph.,  8 :  1903,  355. 
E.  Swift,  Sensibility  to  pain,  in  A.  J.  P.,  11 :  1900,  312-7. 
E.  L.  Thorndike,  Mental  fatigue,  in  P.  R.,  7 :  1900,  466-482,  547-579. 

E.  L.  Thorndike,  Mental  fatigue,  in  J.  E.  P.,  2 :  1911,  61-80. 

A.  D.  Waller,  The  sense  of  effort:  an  objective  study,  in  Brain, 
14 :  1891,  218-249. 

F.  L.  Wells,  (a)  A  neglected  measure  of  fatigue,  in  A.  J.  P.,  19: 

1908,  345-358.  (6)  Normal  performance  in  the  tapping  test 
before  and  during  practice,  with  special  reference  to  fatigue, 
in  A.  J.  P.,  19:  1908,  437-483.  (c)  Studies  in  retardation  as 
given  in  the  fatigue  phenomena  of  the  tapping  test,  in  A.  J.  P., 
20:  1909,  38-59.  (d)  bex  umerences  in  the  tapping  test:  an 
interpretation,  in  A.  J.  P.,  20 :  1909,  353-363. 

J.  H.  Wimms,  The  relation  of  fatigue  and  practice  produced  by 
different  kinds  of  mental  work,  in  Brit.  J.  of  Psych.,  2 :  1907, 
153-195. 

W.  H.  Winch,  see  Offner's  bibliography. 

W.  R.  Wright,  Some  effects  of  incentives  on  work  and  fatigue,  in 
P.  R.,  13 :  1906,  23-34. 

C.  S.  Yoakum,  An  experimental  study  of  fatigue,  in  P.  R.  Mon. 
Supp.,  11 :  1909,  whole  No.  46.    Pp.  131. 


APPENDIX    II. 

The  Terminology  of  the  German  School  System. 

No  attempt  has  been  made  in  the  translation  to  find  English 
equivalents  for  Volksschule,  Gymnasium  and  other  types  of  Ger- 
man schools,  because  there  are  no  exact  English  equivalents.  A 
brief  explanation  of  the  German  school  system  is  therefore  in 
order.  Each  German  state  has  its  own  system,  yet  there  is  a  gen- 
eral similarity  of  organization.  The  Prussian  system  may  be  taken 
as  typical.  In  that  state,  what  would  correspond  to  our  public 
schools  are  divided  into  two  sections,  which  are  often  termed  the 
elementary  and  the  secondary  schools,  respectively,  though  these 
designations  convey  the  false  idea  of  an  'educational  ladder,'  like 
our  own  system,  that  does  not  exist  in  Germany. 

The  elementary  schools  include  the  Volksschule,  the  Mlttel- 
schule  and  the  FortHldungsschule.  These  three  schools  serve  to 
train  children  of  the  laboring  or  lower  business  classes.  Attend- 
ance in  the  Volksschule  is  absolutely  compulsory  from  six  to  four- 
teen years,  unless  the  child  is  otherwise  instructed.  The  Mittel- 
schule  includes  instruction  in  French  and  English,  exacts  a  mod- 
erate tuition  fee,  is  patronized  by  the  lower  middle  classes,  and 
hence  draws  pupils  of  better  ability  and  home  training.  The  mod- 
ern Mittelschule  may  be  considered  a  substitute  for  the  earlier 
Bilrgerschule.  The  Forthildungsschule  (continuation  school)  is  a 
short  course,  required  or  optional,  giving  vocational  and  industrial 
instruction  to  pupils  who  have  finished  the  Volksschule  or  Mittel- 
schule. 

The  higher  or  secondary  schools  include  the  Vorschule  and 
various  types  of  Gymnasium^  and  Bealschule,  as  well  as  the 
Hohere  Madchenschule  or  Tochterschule.  The  Vorschule  is  vir- 
tually an  elementary  preparatory  school,  entered  at  six,  and  turn- 
ing its  pupils  into  higher  schools  proper  at  the  age  of  nine.  Prac- 
tically all  German  children  destined  for  higher  education  use  the 
Vorschule  in  place  of  the  Volksschule  or  Mittelschule.  Of  the 
higher  schools  proper,  the  Gymnasium,  the  Bealgymnasium  and  the 
OMrrealschule  represents  three  co-ordinate,  but  independent,  insti- 
tutions, each  with  a  prescribed  nine-year  curriculum.  Pupils  com- 
monly enter,  then,  at  nine,  and  are  graduated  at  eighteen,  so  that 
the  course  virtually  includes  the  first  two  years  of  the  ordinary 
American  college.  Pupils  may,  subject  to  geographical  limitations, 
elect  the  type  of  school,  and  may  in  theory  elect  certain  optional 
supplementary  work  in  them,  but  in  practice,  the  required  work 
is  heavy  enough  for  most  pupils.  The  nine  classes,  beginning  at 
the  last,  or  senior,  year  are  known  as  Oherprima,  TJnter prima, 
OMrsecunda,  Untersecunda,  Olertertia,  Untertertia,  Quarta, 
Qumta  and  8exta,  respectively. 

130 


APPENDIX  II  131 


The  Refm-mgymnasium  and  the  Reformrealgymnasvum  have 
practically  the  same  curricula  as  the  Gymnasium  and  the  Real- 
gymnasium,  only  so  arranged  that  the  pupil  need  not  decide  finally 
upon  his  course  of  study  until  the  age  of  twelve,  instead  of  at  nine. 

The  Progymnasium,  the  Realprogymnasium  and  the  Realschule 
are  three  schools,  corresponding  to  those  indicated  by  their  names, 
but  offering  only  six  of  the  nine  years'  course ;  they  are  found 
oftenest  in  smaller  cities  that  cannot  afford  the  nine-year  courses. 

The  Eohere  Mddchenschule,  or  TochtersGhule,  is  a  ten-year 
school  for  girls  (thus  allowing  them  one  year  more  than  boys) 
and  covering  as  a  rule  the  ages  six  to  sixteen.  A  very  recent 
movement  (since  1908)  provides  for  the  enlargement  of  these 
courses  by  the  addition  of  three  more  years,  which  will  give  girls 
an  education  equal  to  that  offered  boys. 

For  a  description  of  the  Frauenanstalt,  or  school  for  women, 
and  the  Lehrerinnenseminar,  or  normal  school  for  female  teachers, 
as  well  as  for  further  details  concerning  the  schools  mentioned 
above,  the  reader  may  consult  J.  F.  Brown,  The  Training  of 
TeacJiers  for  Secondary  Schools  in  Germany  and  the  United 
States,  Ch.  I. 


INDEX  OF  NAMES 


Griesbach,  31,  33  ff.,  55,  87,  101, 

105,  110,  113. 
Heller,  31,  34,  81,  86. 
Hellpach,  82. 
Helmholtz,  24. 
Henri,  8,  15,  28,  58. 
Herberich,  84. 
Hering,  11. 
Hermann,  12  f.,  96. 
Hertel,  77. 


Abelson,  33,  35,  85  f.,  102. 
Adsersen,  77. 
Amberg,  66. 

Baade,  65. 

Bach,  111. 

Baur,  30,  39. 

Bellei,  47  f.,  51. 

Bernhard,  89. 

Bettman,  43  f. 

Binet,  8,  15,  28,  33  f.,  42,  51,  58.    Hetimann,  86,  93. 

Blazek,  34,  75,  105.  Hirschlaff,  24  f . 

Bolton,  27,  3.5,  37.  Hoch,  25. 

Bonoff,  34,  77.  Hofler,  78,  118. 

Boubier,  80.  Holmes,  58,  103. 

Bourdon,  52.  Hopfner,  59  f . 

Bralm,  76. 

Bm-gerstein,  47,   57,  60,  72,   77,    Januschke,  49. 

79,  82  f.,  87,  89,  91,  100,  102,    Joteyko,  24,  34. 

107,  114  f. 

Keller,  27,  34,  43,  82,  119. 
Claparede,  24,  42,  74,  78, 100, 107.    Kemsies,  24,  48,  52,  75,  83  f.,  105. 


Claviere,  24  f. 

Dankwartb,  48. 
Dornberger,  84,  89,  121. 
Dornbliith,  103. 

Ebbinghaus,  33,  48  f£.,  58. 
Eulenberg,  23,  32  f.,  111. 

Fechner,  32. 

Fere,  9,  27,  74. 

Ferrari,  34, 

Friedrich,  47  f.,  85,  87,  89. 

Galton,  80. 

Gaupp,  51,  102. 

Germann,  36. 

Gilbert,  28. 

Gineff,  24  ff.,  36  ff.,  41. 

Grassmann,  89,  121. 


Kerschensteiner,  77. 

Key,  66,  88. 

Kraepelin,  13,  24  ff.,  35,  58,  60  fe., 

66  ff.,  72,  76,  93,  98,  100,  108, 

112. 
Kiilpe,  32. 

Landois,  10. 
Laser,  47. 
Lay,  28,  72. 
Leuba,  36. 
Ley,  34. 
Lindley,  93. 
Lipmann,  51. 
Lipps,  31. 
Loeb,  23. 
Lobsien,  28,  41,  43. 

Manaceine,  115. 
Merian-Genast,  57. 


132 


INDEX  OF  NAMES 


133 


Meumann,  14,  27,  29,  36,  38  f., 

42,  54,  66,  75. 
Michotte,  34. 

Mosso,  8  ff.,  15,  23  f.,  27,  96,  100. 
Motchoulsky,  31. 
Mtiller,  J.  J.,  95. 
Miiller,  R.,  25. 

Netschajeff,  48. 
Noikow,  34. 

Offner,  14,  31,  54,  64,  101,  103. 
Oehrn,  43. 
Oseretzkowsky,  27,  62. 

Philippe,  25. 

Ranke,  10. 
Ravenhill,  89. 
Richter,  48,  57  f .,  78,  100. 
Ritter,  36,  49,  52,  106  f. 
Rivers,  13,  93. 
Romer,  88. 

Sakaki,  34,  105  f . 

Seliiller,  109. 

Schlesinger,  34. 

Schmid-Monnard,  84. 

Schroder,  114. 

Schulze,  72,  98. 

Schuyten,  24,  26,  34,  48,  53,  71, 

90,  106,  108. 
Sharp,  51. 
Sikorski,  5,  46. 
Smedley,  102. 
Spearman,  33,  51. 


Specht,  76  f . 
Stern,  28  f.,  72. 
Storring,  39. 
Swift,  42. 

Tawney,  36. 

Teljatnik,  48  f.,  52  f.,  55,  72, 100. 

Terman,  51. 

Thorndike,  21. 

Treutlein,  82  f.,  107. 

Uhlig,  58. 
Ulmann,  23. 
Urbantschitsch,  95. 

Vannod,  34,  38,  42,  75,  87,  101, 

105  f. 
Vaschide,  24,  42,  105  f. 
Verworn,  8,  10,  12  f. 

Wagner,  34,  66,  87,  101,  105,  110, 

115. 
Weber,  32. 
Weichardt,  11. 
Wells,  28. 
Wertheimer,  51. 
Weygandt,  98. 
Wichmann,  115. 
Wiersma,  51. 
Winch,  21,  52,  108. 

Young,  95. 

Ziehen,  33. 
Zielinski,  118. 


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